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diff --git a/doc/rfc/rfc1327.txt b/doc/rfc/rfc1327.txt new file mode 100644 index 0000000..06e3e23 --- /dev/null +++ b/doc/rfc/rfc1327.txt @@ -0,0 +1,6331 @@ + + + + + + +Network Working Group S. Hardcastle-Kille +Request for Comments: 1327 University College London +Obsoletes: RFCs 987, 1026, 1138, 1148 May 1992 +Updates: RFC 822 + + + Mapping between X.400(1988) / ISO 10021 and RFC 822 + +Status of this Memo + + This RFC specifies an IAB standards track protocol for the Internet + community, and requests discussion and suggestions for improvements. + Please refer to the current edition of the "IAB Official Protocol + Standards" for the standardization state and status of this protocol. + Distribution of this memo is unlimited. + +Abstract + + This document describes a set of mappings which will enable + interworking between systems operating the CCITT X.400 1988) + Recommendations on Message Handling Systems / ISO IEC 10021 Message + Oriented Text Interchange Systems (MOTIS) [CCITT/ISO88a], and systems + using the RFC 822 mail protocol [Crocker82a] or protocols derived + from RFC 822. The approach aims to maximise the services offered + across the boundary, whilst not requiring unduly complex mappings. + The mappings should not require any changes to end systems. This + document is a revision based on RFCs 987, 1026, 1138, and 1148 + [Kille86a,Kille87a] which it obsoletes. + + This document specifies a mapping between two protocols. This + specification should be used when this mapping is performed on the + DARPA Internet or in the UK Academic Community. This specification + may be modified in the light of implementation experience, but no + substantial changes are expected. + +Table of Contents + + 1 - Overview ...................................... 3 + 1.1 - X.400 ......................................... 3 + 1.2 - RFC 822 ....................................... 3 + 1.3 - The need for conversion ....................... 4 + 1.4 - General approach .............................. 4 + 1.5 - Gatewaying Model .............................. 5 + 1.6 - X.400 (1984) .................................. 8 + 1.7 - Compatibility with previous versions .......... 8 + 1.8 - Aspects not covered ........................... 8 + 1.9 - Subsetting .................................... 9 + 1.10 - Document Structure ............................ 9 + + + +Hardcastle-Kille [Page 1] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + 1.11 - Acknowledgements .............................. 9 + 2 - Service Elements .............................. 10 + 2.1 - The Notion of Service Across a Gateway ........ 10 + 2.2 - RFC 822 ....................................... 11 + 2.3 - X.400 ......................................... 15 + 3 - Basic Mappings ................................ 24 + 3.1 - Notation ...................................... 24 + 3.2 - ASCII and IA5 ................................. 26 + 3.3 - Standard Types ................................ 26 + 3.4 - Encoding ASCII in Printable String ............ 28 + 4 - Addressing .................................... 30 + 4.1 - A textual representation of MTS.ORAddress ..... 30 + 4.2 - Basic Representation .......................... 31 + 4.3 - EBNF.822-address <-> MTS.ORAddress ............ 36 + 4.4 - Repeated Mappings ............................. 48 + 4.5 - Directory Names ............................... 50 + 4.6 - MTS Mappings .................................. 50 + 4.7 - IPMS Mappings ................................. 55 + 5 - Detailed Mappings ............................. 59 + 5.1 - RFC 822 -> X.400 .............................. 59 + 5.2 - Return of Contents ............................ 67 + 5.3 - X.400 -> RFC 822 .............................. 67 + Appendix A - Mappings Specific to SMTP ..................... 91 + Appendix B - Mappings specific to the JNT Mail ............. 91 + 1 - Introduction .................................. 91 + 2 - Domain Ordering ............................... 91 + 3 - Addressing .................................... 91 + 4 - Acknowledge-To: .............................. 91 + 5 - Trace ......................................... 92 + 6 - Timezone specification ........................ 92 + 7 - Lack of 822-MTS originator specification ...... 92 + Appendix C - Mappings specific to UUCP Mail ................ 93 + Appendix D - Object Identifier Assignment .................. 94 + Appendix E - BNF Summary ................................... 94 + Appendix F - Format of address mapping tables .............. 101 + 1 - Global Mapping Information .................... 101 + 2 - Syntax Definitions ............................ 102 + 3 - Table Lookups ................................. 103 + 4 - Domain -> O/R Address format .................. 104 + 5 - O/R Address -> Domain format .................. 104 + 6 - Domain -> O/R Address of Gateway table ........ 104 + Appendix G - Mapping with X.400(1984) ...................... 105 + Appendix H - RFC 822 Extensions for X.400 access ........... 106 + Appendix I - Conformance ................................... 106 + Appendix J - Change History: RFC 987, 1026, 1138, 1148 ..... 107 + 1 - Introduction .................................. 108 + 2 - Service Elements .............................. 108 + 3 - Basic Mappings ................................ 108 + + + +Hardcastle-Kille [Page 2] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + 4 - Addressing .................................... 108 + 5 - Detailed Mappings ............................. 109 + 6 - Appendices .................................... 109 + Appendix K - Change History: RFC 1148 to this Document ..... 109 + 1 - General ....................................... 109 + 2 - Basic Mappings ................................ 110 + 3 - Addressing .................................... 110 + 4 - Detailed Mappings ............................. 110 + 5 - Appendices .................................... 110 + References ................................................. 111 + Security Considerations .................................... 113 + Author's Address ........................................... 113 + +Chapter 1 -- Overview + +1.1. X.400 + + This document relates to the CCITT 1988 X.400 Series Recommendations + / ISO IEC 10021 on the Message Oriented Text Interchange Service + (MOTIS). This ISO/CCITT standard is referred to in this document as + "X.400", which is a convenient shorthand. Any reference to the 1984 + CCITT Recommendations will be explicit. X.400 defines an + Interpersonal Messaging System (IPMS), making use of a store and + forward Message Transfer System. This document relates to the IPMS, + and not to wider application of X.400. It is expected that X.400 + will be implemented very widely. + +1.2. RFC 822 + + RFC 822 evolved as a messaging standard on the DARPA (the US Defense + Advanced Research Projects Agency) Internet. It specifies and end to + end message format. It is used in conjunction with a number of + different message transfer protocol environments. + + SMTP Networks + On the DARPA Internet and other TCP/IP networks, RFC 822 is + used in conjunction with two other standards: RFC 821, also + known as Simple Mail Transfer Protocol (SMTP) [Postel82a], + and RFC 920 which is a Specification for domains and a + distributed name service [Postel84a]. + + UUCP Networks + UUCP is the UNIX to UNIX CoPy protocol, which is usually + used over dialup telephone networks to provide a simple + message transfer mechanism. There are some extensions to + RFC 822, particularly in the addressing. They use domains + which conform to RFC 920, but not the corresponding domain + nameservers [Horton86a]. + + + +Hardcastle-Kille [Page 3] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + Bitnet + Some parts of Bitnet and related networks use RFC 822 + related protocols, with EBCDIC encoding. + + JNT Mail Networks + A number of X.25 networks, particularly those associated + with the UK Academic Community, use the JNT (Joint Network + Team) Mail Protocol, also known as Greybook [Kille84a]. + This is used with domains and name service specified by the + JNT NRS (Name Registration Scheme) [Larmouth83a]. + + The mappings specified here are appropriate for all of these + networks. + +1.3. The need for conversion + + There is a large community using RFC 822 based protocols for mail + services, who will wish to communicate with users of the IPMS + provided by X.400 systems. This will also be a requirement in cases + where communities intend to make a transition to use of an X.400 + IPMS, as conversion will be needed to ensure a smooth service + transition. It is expected that there will be more than one gateway, + and this specification will enable them to behave in a consistent + manner. Note that the term gateway is used to describe a component + performing the protocol mappings between RFC 822 and X.400. This is + standard usage amongst mail implementors, but should be noted + carefully by transport and network service implementors. + + Consistency between gateways is desirable to provide: + + 1. Consistent service to users. + + 2. The best service in cases where a message passes through + multiple gateways. + +1.4. General approach + + There are a number of basic principles underlying the details of the + specification. These principles are goals, and are not achieved in + all aspects of the specification. + + 1. The specification should be pragmatic. There should not be + a requirement for complex mappings for "Academic" reasons. + Complex mappings should not be required to support trivial + additional functionality. + + 2. Subject to 1), functionality across a gateway should be as + high as possible. + + + +Hardcastle-Kille [Page 4] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + 3. It is always a bad idea to lose information as a result of + any transformation. Hence, it is a bad idea for a gateway + to discard information in the objects it processes. This + includes requested services which cannot be fully mapped. + + 4. All mail gateways actually operate at exactly one level + above the layer on which they conceptually operate. This + implies that the gateway must not only be cognisant of the + semantics of objects at the gateway level, but also be + cognisant of higher level semantics. If meaningful + transformation of the objects that the gateway operates on + is to occur, then the gateway needs to understand more than + the objects themselves. + + 5. Subject to 1), the specification should be reversible. That + is, a double transformation should bring you back to where + you started. + +1.5. Gatewaying Model + +1.5.1. X.400 + + X.400 defines the IPMS Abstract Service in X.420/ISO 10021-7, + [CCITT/ISO88b] which comprises of three basic services: + + 1. Origination + + 2. Reception + + 3. Management + + Management is a local interaction between the user and the IPMS, and + is therefore not relevant to gatewaying. The first two services + consist of operations to originate and receive the following two + objects: + + 1. IPM (Interpersonal Message). This has two components: a + heading, and a body. The body is structured as a sequence + of body parts, which may be basic components (e.g., IA5 + text, or G3 fax), or IP Messages. The heading consists of + fields containing end to end user information, such as + subject, primary recipients (To:), and importance. + + 2. IPN (Inter Personal Notification). A notification about + receipt of a given IPM at the UA level. + + The Origination service also allows for origination of a probe, which + is an object to test whether a given IPM could be correctly received. + + + +Hardcastle-Kille [Page 5] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + The Reception service also allows for receipt of Delivery Reports + DR), which indicate delivery success or failure. + + These IPMS Services utilise the Message Transfer (MT) Abstract + Service [CCITT/ISO88c]. The MT Abstract Service provides the + following three basic services: + + 1. Submission (used by IPMS Origination) + + 2. Delivery (used by IPMS Reception) + + 3. Administration (used by IPMS Management) + + Administration is a local issue, and so does not affect this + standard. Submission and delivery relate primarily to the MTS + Message (comprising Envelope and Content), which carries an IPM or + IPN (or other uninterpreted contents). There is also an Envelope, + which includes an ID, an originator, and a list of recipients. + Submission also includes the probe service, which supports the IPMS + Probe. Delivery also includes Reports, which indicate whether a given + MTS Message has been delivered or not. + + The MTS is REFINED into the MTA (Message Transfer Agent) Service, + which defines the interaction between MTAs, along with the procedures + for distributed operation. This service provides for transfer of MTS + Messages, Probes, and Reports. + +1.5.2. RFC 822 + + RFC 822 is based on the assumption that there is an underlying + service, which is here called the 822-MTS service. The 822-MTS + service provides three basic functions: + + 1. Identification of a list of recipients. + + 2. Identification of an error return address. + + 3. Transfer of an RFC 822 message. + + It is possible to achieve 2) within the RFC 822 header. Some 822-MTS + protocols, in particular SMTP, can provide additional functionality, + but as these are neither mandatory in SMTP, nor available in other + 822-MTS protocols, they are not considered here. Details of aspects + specific to two 822-MTS protocols are given in Appendices B and C. + An RFC 822 message consists of a header, and content which is + uninterpreted ASCII text. The header is divided into fields, which + are the protocol elements. Most of these fields are analogous to P2 + heading fields, although some are analogous to MTS Service Elements + + + +Hardcastle-Kille [Page 6] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + or MTA Service Elements. + +1.5.3. The Gateway + + Given this functional description of the two services, the functional + nature of a gateway can now be considered. It would be elegant to + consider the 822-MTS service mapping onto the MTS Service Elements + and RFC 822 mapping onto an IPM, but reality just does not fit. + Another elegant approach would be to treat this document as the + definition of an X.400 Access Unit (AU). Again, reality does not + fit. It is necessary to consider that the IPM format definition, the + IPMS Service Elements, the MTS Service Elements, and MTA Service + Elements on one side are mapped into RFC 822 + 822-MTS on the other + in a slightly tangled manner. The details of the tangle will be made + clear in Chapter 5. Access to the MTA Service Elements is minimised. + + The following basic mappings are thus defined. When going from RFC + 822 to X.400, an RFC 822 message and the associated 822-MTS + information is always mapped into an IPM (MTA, MTS, and IPMS + Services). Going from X.400 to RFC 822, an RFC 822 message and the + associated 822-MTS information may be derived from: + + 1. A Report (MTA, and MTS Services) + + 2. An IPN (MTA, MTS, and IPMS services) + + 3. An IPM (MTA, MTS, and IPMS services) + + Probes (MTA Service) must be processed by the gateway, as discussed + in Chapter 5. MTS Messages containing Content Types other than those + defined by the IPMS are not mapped by the gateway, and should be + rejected at the gateway. + +1.5.4. Repeated Mappings + + The primary goal of this specification is to support single mappings, + so that X.400 and RFC 822 users can communicate with maximum + functionality. + + The mappings specified here are designed to work where a message + traverses multiple times between X.400 and RFC 822. This is often + essential, particularly in the case of distribution lists. However, + in general, this will lead to a level of service which is the lowest + common denominator (approximately the services offered by RFC 822). + + Some RFC 822 networks may wish to use X.400 as an interconnection + mechanism (typically for policy reasons), and this is fully + supported. + + + +Hardcastle-Kille [Page 7] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + Where an X.400 messages transfers to RFC 822 and then back to X.400, + there is no expectation of X.400 services which do not have an + equivalent service in standard RFC 822 being preserved - although + this may be possible in some cases. + +1.6. X.400 (1984) + + Much of this work is based on the initial specification of RFC 987 + and in its addendum RFC 1026, which defined a mapping between + X.400(1984) and RFC 822. A basic decision is that the mapping + defined in this document is to the full 1988 version of X.400, and + not to a 1984 compatible subset. New features of X.400(1988) can be + used to provide a much cleaner mapping than that defined in RFC 987. + This is important, to give good support to communities which will + utilise full X.400 at an early date. To interwork with 1984 + systems, Appendix G shall be followed. + + If a message is being transferred to an X.400(1984) system by way of + X.400(1988) MTA it will give a slightly better service to follow the + rules of Appendix G. + +1.7. Compatibility with previous versions + + The changes between this and older versions of the document are given + in Appendices I and J. These are RFCs 987, 1026, 1138, and 1148. + This document is a revision of RFC 1148 [Kille90a]. As far as + possible, changes have been made in a compatible fashion. + +1.8. Aspects not covered + + There have been a number of cases where RFC 987 was used in a manner + which was not intended. This section is to make clear some + limitations of scope. In particular, this specification does not + specify: + + - Extensions of RFC 822 to provide access to all X.400 + services + + - X.400 user interface definition + + - Mapping X.400 to extended versions of RFC 822, with support + for multimedia content. + + The first two of these are really coupled. To map the X.400 + services, this specification defines a number of extensions to RFC + 822. As a side effect, these give the 822 user access to SOME X.400 + services. However, the aim on the RFC 822 side is to preserve + current service, and it is intentional that access is not given to + + + +Hardcastle-Kille [Page 8] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + all X.400 services. Thus, it will be a poor choice for X.400 + implementors to use RFC 987(88) as an interface - there are too many + aspects of X.400 which cannot be accessed through it. If a text + interface is desired, a specification targeted at X.400, without RFC + 822 restrictions, would be more appropriate. Some optional and + limited extensions in this area have proved useful, and are defined + in Appendix H. + +1.9. Subsetting + + This proposal specifies a mapping which is appropriate to preserve + services in existing RFC 822 communities. Implementations and + specifications which subset this specification are strongly + discouraged. + +1.10. Document Structure + + This document has five chapters: + + 1. Overview - this chapter. + + 2. Service Elements - This describes the (end user) services + mapped by a gateway. + + 3. Basic mappings - This describes some basic notation used in + Chapters 3-5, the mappings between character sets, and some + fundamental protocol elements. + + 4. Addressing - This considers the mapping between X.400 O/R + names and RFC 822 addresses, which is a fundamental gateway + component. + + 5. Detailed Mappings - This describes the details of all other + mappings. + + There are also eleven appendices. + + WARNING: + THE REMAINDER OF THIS SPECIFICATION IS TECHNICALLY DETAILED. + IT WILL NOT MAKE SENSE, EXCEPT IN THE CONTEXT OF RFC 822 AND + X.400 (1988). DO NOT ATTEMPT TO READ THIS DOCUMENT UNLESS + YOU ARE FAMILIAR WITH THESE SPECIFICATIONS. + +1.11. Acknowledgements + + The work in this specification was substantially based on RFC 987 and + RFC 1148, which had input from many people, who are credited in the + respective documents. + + + +Hardcastle-Kille [Page 9] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + A number of comments from people on RFC 1148 lead to this document. + In particular, there were comments and suggestions from: Maurice + Abraham (HP); Harald Alvestrand (Sintef); Peter Cowen (X-Tel); Jim + Craigie (JNT); Ella Gardener (MITRE); Christian Huitema (Inria); Erik + Huizer (SURFnet); Neil Jones DEC); Ignacio Martinez (IRIS); Julian + Onions (X-Tel); Simon Poole (SWITCH); Clive Roberts (Data General); + Pete Vanderbilt SUN); Alan Young (Concurrent). + +Chapter 2 - Service Elements + + This chapter considers the services offered across a gateway built + according to this specification. It gives a view of the + functionality provided by such a gateway for communication with users + in the opposite domain. This chapter considers service mappings in + the context of SINGLE transfers only, and not repeated mappings + through multiple gateways. + +2.1. The Notion of Service Across a Gateway + + RFC 822 and X.400 provide a number of services to the end user. This + chapter describes the extent to which each service can be supported + across an X.400 <-> RFC 822 gateway. The cases considered are single + transfers across such a gateway, although the problems of multiple + crossings are noted where appropriate. + +2.1.1. Origination of Messages + + When a user originates a message, a number of services are available. + Some of these imply actions (e.g., delivery to a recipient), and some + are insertion of known data (e.g., specification of a subject field). + This chapter describes, for each offered service, to what extent it + is supported for a recipient accessed through a gateway. There are + three levels of support: + + Supported + The corresponding protocol elements map well, and so the + service can be fully provided. + + Not Supported + The service cannot be provided, as there is a complete + mismatch. + + Partial Support + The service can be partially fulfilled. + + In the first two cases, the service is simply marked as Supported" or + "Not Supported". Some explanation may be given if there are + additional implications, or the (non) support is not intuitive. For + + + +Hardcastle-Kille [Page 10] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + partial support, the level of partial support is summarised. Where + partial support is good, this will be described by a phrase such as + "Supported by use of.....". A common case of this is where the + service is mapped onto a non- standard service on the other side of + the gateway, and this would have lead to support if it had been a + standard service. In many cases, this is equivalent to support. For + partial support, an indication of the mechanism is given, in order to + give a feel for the level of support provided. Note that this is not + a replacement for Chapter 5, where the mapping is fully specified. + + If a service is described as supported, this implies: + + - Semantic correspondence. + + - No (significant) loss of information. + + - Any actions required by the service element. + + An example of a service gaining full support: If an RFC 822 + originator specifies a Subject: field, this is considered to be + supported, as an X.400 recipient will get a subject indication. + + In many cases, the required action will simply be to make the + information available to the end user. In other cases, actions may + imply generating a delivery report. + + All RFC 822 services are supported or partially supported for + origination. The implications of non-supported X.400 services is + described under X.400. + +2.1.2. Reception of Messages + + For reception, the list of service elements required to support this + mapping is specified. This is really an indication of what a + recipient might expect to see in a message which has been remotely + originated. + +2.2. RFC 822 + + RFC 822 does not explicitly define service elements, as distinct from + protocol elements. However, all of the RFC 822 header fields, with + the exception of trace, can be regarded as corresponding to implicit + RFC 822 service elements. + +2.2.1. Origination in RFC 822 + + A mechanism of mapping, used in several cases, is to map the RFC 822 + header into a heading extension in the IPM (InterPersonal Message). + + + +Hardcastle-Kille [Page 11] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + This can be regarded as partial support, as it makes the information + available to any X.400 implementations which are interested in these + services. Communities which require significant RFC 822 interworking + are recommended to require that their X.400 User Agents are able to + display these heading extensions. Support for the various service + elements (headers) is now listed. + + Date: + Supported. + + From: + Supported. For messages where there is also a sender field, + the mapping is to "Authorising Users Indication", which has + subtly different semantics to the general RFC 822 usage of + From:. + + Sender: + Supported. + + Reply-To: + Supported. + + To: Supported. + + Cc: Supported. + + Bcc: Supported. + + Message-Id: + Supported. + + In-Reply-To: + Supported, for a single reference. Where multiple + references are given, partial support is given by mapping to + "Cross Referencing Indication". This gives similar + semantics. + + References: + Supported. + + Keywords: + Supported by use of a heading extension. + + Subject: + Supported. + + Comments: + Supported by use of an extra body part. + + + +Hardcastle-Kille [Page 12] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + Encrypted: + Supported by use of a heading extension. + + Resent-* + Supported by use of a heading extension. Note that + addresses in these fields are mapped onto text, and so are + not accessible to the X.400 user as addresses. In + principle, fuller support would be possible by mapping onto + a forwarded IP Message, but this is not suggested. + + Other Fields + In particular X-* fields, and "illegal" fields in common + usage (e.g., "Fruit-of-the-day:") are supported by use of + heading extensions. + +2.2.2. Reception by RFC 822 + + This considers reception by an RFC 822 User Agent of a message + originated in an X.400 system and transferred across a gateway. The + following standard services (headers) may be present in such a + message: + + Date: + + From: + + Sender: + + Reply-To: + + To: + + Cc: + + Bcc: + + Message-Id: + + In-Reply-To: + + References: + + Subject: + + The following non-standard services (headers) may be present. These + are defined in more detail in Chapter 5 (5.3.4, 5.3.6, 5.3.7): + + + + + +Hardcastle-Kille [Page 13] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + Autoforwarded: + + Content-Identifier: + + Conversion: + + Conversion-With-Loss: + + Delivery-Date: + + Discarded-X400-IPMS-Extensions: + + Discarded-X400-MTS-Extensions: + + DL-Expansion-History: + + Deferred-Delivery: + + Expiry-Date: + + Importance: + + Incomplete-Copy: + + Language: + + Latest-Delivery-Time: + + Message-Type: + + Obsoletes: + + Original-Encoded-Information-Types: + + Originator-Return-Address: + + Priority: + + Reply-By: + + Requested-Delivery-Method: + + Sensitivity: + + X400-Content-Type: + + X400-MTS-Identifier: + + + + +Hardcastle-Kille [Page 14] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + X400-Originator: + + X400-Received: + + X400-Recipients: + +2.3. X.400 + +2.3.1. Origination in X.400 + + When mapping services from X.400 to RFC 822 which are not supported + by RFC 822, new RFC 822 headers are defined. It is intended that + these fields will be registered, and that co- operating RFC 822 + systems may use them. Where these new fields are used, and no system + action is implied, the service can be regarded as being partially + supported. Chapter 5 describes how to map X.400 services onto these + new headers. Other elements are provided, in part, by the gateway as + they cannot be provided by RFC 822. + + Some service elements are marked N/A (not applicable). There are + five cases, which are marked with different comments: + + N/A (local) + These elements are only applicable to User Agent / Message + Transfer Agent interaction and so they cannot apply to RFC + 822 recipients. + + N/A (PDAU) + These service elements are only applicable where the + recipient is reached by use of a Physical Delivery Access + Unit (PDAU), and so do not need to be mapped by the gateway. + + N/A (reception) + These services are only applicable for reception. + + N/A (prior) + If requested, this service must be performed prior to the + gateway. + + N/A (MS) + These services are only applicable to Message Store (i.e., a + local service). + + Finally, some service elements are not supported. In particular, the + new security services are not mapped onto RFC 822. Unless otherwise + indicated, the behaviour of service elements marked as not supported + will depend on the criticality marking supplied by the user. If the + element is marked as critical for transfer or delivery, a non- + + + +Hardcastle-Kille [Page 15] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + delivery notification will be generated. Otherwise, the service + request will be ignored. + +2.3.1.1. Basic Interpersonal Messaging Service + + These are the mandatory IPM services as listed in Section 19.8 of + X.400 / ISO/IEC 10021-1, listed here in the order given. Section 19.8 + has cross references to short definitions of each service. + + Access management + N/A (local). + + Content Type Indication + Supported by a new RFC 822 header (Content-Type:). + + Converted Indication + Supported by a new RFC 822 header (X400-Received:). + + Delivery Time Stamp Indication + N/A (reception). + + IP Message Identification + Supported. + + Message Identification + Supported, by use of a new RFC 822 header + (X400-MTS-Identifier). This new header is required, as + X.400 has two message-ids whereas RFC 822 has only one (see + previous service). + + Non-delivery Notification + Not supported, although in general an RFC 822 system will + return error reports by use of IP messages. In other + service elements, this pragmatic result can be treated as + effective support of this service element. + + Original Encoded Information Types Indication + Supported as a new RFC 822 header + (Original-Encoded-Information-Types:). + + Submission Time Stamp Indication + Supported. + + Typed Body + Some types supported. IA5 is fully supported. + ForwardedIPMessage is supported, with some loss of + information. Other types get some measure of support, + dependent on X.400 facilities for conversion to IA5. This + + + +Hardcastle-Kille [Page 16] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + will only be done where content conversion is not + prohibited. + + User Capabilities Registration + N/A (local). + +2.3.1.2. IPM Service Optional User Facilities + + This section describes support for the optional (user selectable) IPM + services as listed in Section 19.9 of X.400 / ISO/IEC 10021- 1, + listed here in the order given. Section 19.9 has cross references to + short definitions of each service. + + Additional Physical Rendition + N/A (PDAU). + + Alternate Recipient Allowed + Not supported. There is no RFC 822 service equivalent to + prohibition of alternate recipient assignment (e.g., an RFC + 822 system may freely send an undeliverable message to a + local postmaster). Thus, the gateway cannot prevent + assignment of alternative recipients on the RFC 822 side. + This service really means giving the user control as to + whether or not an alternate recipient is allowed. This + specification requires transfer of messages to RFC 822 + irrespective of this service request, and so this service is + not supported. + + Authorising User's Indication + Supported. + + Auto-forwarded Indication + Supported as new RFC 822 header (Auto-Forwarded:). + + Basic Physical Rendition + N/A (PDAU). + + Blind Copy Recipient Indication + Supported. + + Body Part Encryption Indication + Supported by use of a new RFC 822 header + (Original-Encoded-Information-Types:), although in most + cases it will not be possible to map the body part in + question. + + Content Confidentiality + Not supported. + + + +Hardcastle-Kille [Page 17] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + Content Integrity + Not supported. + + Conversion Prohibition + Supported. In this case, only messages with IA5 body parts, + other body parts which contain only IA5, and Forwarded IP + Messages (subject recursively to the same restrictions), + will be mapped. + + Conversion Prohibition in Case of Loss of Information + Supported. + + Counter Collection + N/A (PDAU). + + Counter Collection with Advice + N/A (PDAU). + + Cross Referencing Indication + Supported. + + Deferred Delivery + N/A (prior). This service should always be provided by the + MTS prior to the gateway. A new RFC 822 header + Deferred-Delivery:) is provided to transfer information on + this service to the recipient. + +Deferred Delivery Cancellation + N/A (local). + +Delivery Notification + Supported. This is performed at the gateway. Thus, a + notification is sent by the gateway to the originator. If + the 822-MTS protocol is JNT Mail, a notification may also be + sent by the recipient UA. + +Delivery via Bureaufax Service + N/A (PDAU). + +Designation of Recipient by Directory Name + N/A (local). + +Disclosure of Other Recipients + Supported by use of a new RFC 822 header (X400-Recipients:). + This is descriptive information for the RFC 822 recipient, + and is not reverse mappable. + + + + + +Hardcastle-Kille [Page 18] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + +DL Expansion History Indication + Supported by use of a new RFC 822 header + DL-Expansion-History:). + +DL Expansion Prohibited + Distribution List means MTS supported distribution list, in + the manner of X.400. This service does not exist in the RFC + 822 world. RFC 822 distribution lists should be regarded as + an informal redistribution mechanism, beyond the scope of + this control. Messages will be sent to RFC 822, + irrespective of whether this service is requested. + Theoretically therefore, this service is supported, although + in practice it may appear that it is not supported. + +Express Mail Service + N/A (PDAU). + +Expiry Date Indication + Supported as new RFC 822 header (Expiry-Date:). In general, + no automatic action can be expected. + +Explicit Conversion + N/A (prior). + +Forwarded IP Message Indication + Supported, with some loss of information. The message is + forwarded in an RFC 822 body, and so can only be interpreted + visually. + +Grade of Delivery Selection + N/A (PDAU) + +Importance Indication + Supported as new RFC 822 header (Importance:). + +Incomplete Copy Indication + Supported as new RFC 822 header (Incomplete-Copy:). + +Language Indication + Supported as new RFC 822 header (Language:). + +Latest Delivery Designation + Not supported. A new RFC 822 header (Latest-Delivery-Time:) + is provided, which may be used by the recipient. + +Message Flow Confidentiality + Not supported. + + + + +Hardcastle-Kille [Page 19] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + +Message Origin Authentication + N/A (reception). + +Message Security Labelling + Not supported. + +Message Sequence Integrity + Not supported. + +Multi-Destination Delivery + Supported. + +Multi-part Body + Supported, with some loss of information, in that the + structuring cannot be formalised in RFC 822. + +Non Receipt Notification Request + Not supported. + +Non Repudiation of Delivery + Not supported. + +Non Repudiation of Origin + N/A (reception). + +Non Repudiation of Submission + N/A (local). + +Obsoleting Indication + Supported as new RFC 822 header (Obsoletes:). + +Ordinary Mail + N/A (PDAU). + +Originator Indication + Supported. + +Originator Requested Alternate Recipient + Not supported, but is placed as comment next to address + X400-Recipients:). + +Physical Delivery Notification by MHS + N/A (PDAU). + +Physical Delivery Notification by PDS + N/A (PDAU). + + + + + +Hardcastle-Kille [Page 20] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + +Physical Forwarding Allowed + Supported by use of a comment in a new RFC 822 header + X400-Recipients:), associated with the recipient in + question. + +Physical Forwarding Prohibited + Supported by use of a comment in a new RFC 822 header + X400-Recipients:), associated with the recipient in + question. + +Prevention of Non-delivery notification + Supported, as delivery notifications cannot be generated by + RFC 822. In practice, errors will be returned as IP + Messages, and so this service may appear not to be supported + see Non-delivery Notification). + +Primary and Copy Recipients Indication + Supported + +Probe + Supported at the gateway (i.e., the gateway services the + probe). + +Probe Origin Authentication + N/A (reception). + +Proof of Delivery + Not supported. + +Proof of Submission + N/A (local). + +Receipt Notification Request Indication + Not supported. + +Redirection Allowed by Originator + Redirection means MTS supported redirection, in the manner + of X.400. This service does not exist in the RFC 822 world. + RFC 822 redirection (e.g., aliasing) should be regarded as + an informal redirection mechanism, beyond the scope of this + control. Messages will be sent to RFC 822, irrespective of + whether this service is requested. Theoretically therefore, + this service is supported, although in practice it may + appear that it is not supported. + +Registered Mail + N/A (PDAU). + + + + +Hardcastle-Kille [Page 21] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + +Registered Mail to Addressee in Person + N/A (PDAU). + +Reply Request Indication + Supported as comment next to address. + +Replying IP Message Indication + Supported. + +Report Origin Authentication + N/A (reception). + +Request for Forwarding Address + N/A (PDAU). + +Requested Delivery Method + N/A (local). The services required must be dealt with at + submission time. Any such request is made available through + the gateway by use of a comment associated with the + recipient in question. + +Return of Content + In principle, this is N/A, as non-delivery notifications are + not supported. In practice, most RFC 822 systems will + return part or all of the content along with the IP Message + indicating an error (see Non-delivery Notification). + +Sensitivity Indication + Supported as new RFC 822 header (Sensitivity:). + +Special Delivery + N/A (PDAU). + +Stored Message Deletion + N/A (MS). + +Stored Message Fetching + N/A (MS). + +Stored Message Listing + N/A (MS). + +Stored Message Summary + N/A (MS). + +Subject Indication + Supported. + + + + +Hardcastle-Kille [Page 22] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + +Undeliverable Mail with Return of Physical Message + N/A (PDAU). + +Use of Distribution List + In principle this applies only to X.400 supported + distribution lists (see DL Expansion Prohibited). + Theoretically, this service is N/A (prior). In practice, + because of informal RFC 822 lists, this service can be + regarded as supported. + +2.3.2. Reception by X.400 + +2.3.2.1. Standard Mandatory Services + + The following standard IPM mandatory user facilities are required + for reception of RFC 822 originated mail by an X.400 UA. + + Content Type Indication + + Delivery Time Stamp Indication + + IP Message Identification + + Message Identification + + Non-delivery Notification + + Original Encoded Information Types Indication + + Submission Time Stamp Indication + + Typed Body + +2.3.2.2. Standard Optional Services + + The following standard IPM optional user facilities are required for + reception of RFC 822 originated mail by an X.400 UA. + + Authorising User's Indication + + Blind Copy Recipient Indication + + Cross Referencing Indication + + Originator Indication + + Primary and Copy Recipients Indication + + + + +Hardcastle-Kille [Page 23] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + Replying IP Message Indication + + Subject Indication + +2.3.2.3. New Services + + A new service "RFC 822 Header Field" is defined using the extension + facilities. This allows for any RFC 822 header field to be + represented. It may be present in RFC 822 originated messages, which + are received by an X.400 UA. + +Chapter 3 Basic Mappings + +3.1. Notation + + The X.400 protocols are encoded in a structured manner according to + ASN.1, whereas RFC 822 is text encoded. To define a detailed + mapping, it is necessary to refer to detailed protocol elements in + each format. A notation to achieve this is described in this + section. + +3.1.1. RFC 822 + + Structured text is defined according to the Extended Backus Naur Form + (EBNF) defined in Section 2 of RFC 822 [Crocker82a]. In the EBNF + definitions used in this specification, the syntax rules given in + Appendix D of RFC 822 are assumed. When these EBNF tokens are + referred to outside an EBNF definition, they are identified by the + string "822." appended to the beginning of the string (e.g., + 822.addr-spec). Additional syntax rules, to be used throughout this + specification, are defined in this chapter. + + The EBNF is used in two ways. + + 1. To describe components of RFC 822 messages (or of 822-MTS + components). In this case, the lexical analysis defined in + Section 3 of RFC 822 shall be used. When these new EBNF + tokens are referred to outside an EBNF definition, they are + identified by the string "EBNF." appended to the beginning + of the string (e.g., EBNF.importance). + + 2. To describe the structure of IA5 or ASCII information not in + an RFC 822 message. In these cases, tokens will either be + self delimiting, or be delimited by self delimiting tokens. + Comments and LWSP are not used as delimiters, except for the + following cases, where LWSP may be inserted according to RFC + 822 rules. + + + + +Hardcastle-Kille [Page 24] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + - Around the ":" in all headers + + - EBNF.labelled-integer + + - EBNF.object-identifier + + - EBNF.encoded-info + + RFC 822 folding rules are applied to all headers. + +3.1.2. ASN.1 + + An element is referred to with the following syntax, defined in EBNF: + + element = service "." definition *( "." definition ) + service = "IPMS" / "MTS" / "MTA" + definition = identifier / context + identifier = ALPHA *< ALPHA or DIGIT or "-" > + context = "[" 1*DIGIT "]" + + The EBNF.service keys are shorthand for the following service + specifications: + + IPMS IPMSInformationObjects defined in Annex E of X.420 / ISO + 10021-7. + + MTS MTSAbstractService defined in Section 9 of X.411 / ISO + 10021-4. + + MTA MTAAbstractService defined in Section 13 of X.411 / ISO + 10021-4. + + The first EBNF.identifier identifies a type or value key in the + context of the defined service specification. Subsequent + EBNF.identifiers identify a value label or type in the context of the + first identifier (SET or SEQUENCE). EBNF.context indicates a context + tag, and is used where there is no label or type to uniquely identify + a component. The special EBNF.identifier keyword "value" is used to + denote an element of a sequence. + + For example, IPMS.Heading.subject defines the subject element of the + IPMS heading. The same syntax is also used to refer to element + values. For example, + + MTS.EncodedInformationTypes.[0].g3Fax refers to a value of + MTS.EncodedInformationTypes.[0] . + + + + + +Hardcastle-Kille [Page 25] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + +3.2. ASCII and IA5 + + A gateway will interpret all IA5 as ASCII. Thus, mapping between + these forms is conceptual. + +3.3. Standard Types + + There is a need to convert between ASCII text, and some of the types + defined in ASN.1 [CCITT/ISO88d]. For each case, an EBNF syntax + definition is given, for use in all of this specification, which + leads to a mapping between ASN.1, and an EBNF construct. All EBNF + syntax definitions of ASN.1 types are in lower case, whereas ASN.1 + types are referred to with the first letter in upper case. Except as + noted, all mappings are symmetrical. + +3.3.1. Boolean + + Boolean is encoded as: + + boolean = "TRUE" / "FALSE" + +3.3.2. NumericString + + NumericString is encoded as: + + numericstring = *DIGIT + +3.3.3. PrintableString + + PrintableString is a restricted IA5String defined as: + + printablestring = *( ps-char ) + ps-restricted-char = 1DIGIT / 1ALPHA / " " / "'" / "+" + / "," / "-" / "." / "/" / ":" / "=" / "?" + ps-delim = "(" / ")" + ps-char = ps-delim / ps-restricted-char + + This can be used to represent real printable strings in EBNF. + +3.3.4. T.61String + + In cases where T.61 strings are only used for conveying human + interpreted information, the aim of a mapping is to render the + characters appropriately in the remote character set, rather than to + maximise reversibility. For these cases, the mappings to IA5 defined + in CCITT Recommendation X.408 (1988) shall be used [CCITT/ISO88a]. + These will then be encoded in ASCII. + + + + +Hardcastle-Kille [Page 26] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + There is also a need to represent Teletex Strings in ASCII, for some + aspects of O/R Address. For these, the following encoding is used: + + teletex-string = *( ps-char / t61-encoded ) + t61-encoded = "{" 1* t61-encoded-char "}" + t61-encoded-char = 3DIGIT + + Common characters are mapped simply. Other octets are mapped using a + quoting mechanism similar to the printable string mechanism. Each + octet is represented as 3 decimal digits. + + There are a number of places where a string may have a Teletex and/or + Printable String representation. The following BNF is used to + represent this. + + teletex-and-or-ps = [ printablestring ] [ "*" teletex-string ] + + The natural mapping is restricted to EBNF.ps-char, in order to make + the full BNF easier to parse. + +3.3.5. UTCTime + + Both UTCTime and the RFC 822 822.date-time syntax contain: Year + (lowest two digits), Month, Day of Month, hour, minute, second + (optional), and Timezone. 822.date-time also contains an optional + day of the week, but this is redundant. Therefore a symmetrical + mapping can be made between these constructs. + + Note: + In practice, a gateway will need to parse various illegal + variants on 822.date-time. In cases where 822.date-time + cannot be parsed, it is recommended that the derived UTCTime + is set to the value at the time of translation. + + When mapping to X.400, the UTCTime format which specifies the + timezone offset shall be used. + + When mapping to RFC 822, the 822.date-time format shall include a + numeric timezone offset (e.g., +0000). + + When mapping time values, the timezone shall be preserved as + specified. The date shall not be normalised to any other timezone. + +3.3.6. Integer + + A basic ASN.1 Integer will be mapped onto EBNF.numericstring. In + many cases ASN.1 will enumerate Integer values or use ENUMERATED. An + EBNF encoding labelled-integer is provided. When mapping from EBNF to + + + +Hardcastle-Kille [Page 27] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + ASN.1, only the integer value is mapped, and the associated text is + discarded. When mapping from ASN.1 to EBNF, addition of an + appropriate text label is strongly encouraged. + + labelled-integer ::= [ key-string ] "(" numericstring ")" + + key-string = *key-char + key-char = <a-z, A-Z, 0-9, and "-"> + + +3.3.7. Object Identifier + + Object identifiers are represented in a form similar to that given in + ASN.1. The order is the same as for ASN.1 (big-endian). The numbers + are mandatory, and used when mapping from the ASCII to ASN.1. The + key-strings are optional. It is recommended that as many strings as + possible are generated when mapping from ASN.1 to ASCII, to + facilitate user recognition. + + object-identifier ::= oid-comp object-identifier + | oid-comp + + oid-comp ::= [ key-string ] "(" numericstring ")" + +An example representation of an object identifier is: + + joint-iso-ccitt(2) mhs (6) ipms (1) ep (11) ia5-text (0) + + or + + (2) (6) (1)(11)(0) + +3.4. Encoding ASCII in Printable String + + Some information in RFC 822 is represented in ASCII, and needs to be + mapped into X.400 elements encoded as printable string. For this + reason, a mechanism to represent ASCII encoded as PrintableString is + needed. + + A structured subset of EBNF.printablestring is now defined. This + shall be used to encode ASCII in the PrintableString character set. + + + + + + + + + + +Hardcastle-Kille [Page 28] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + ps-encoded = *( ps-restricted-char / ps-encoded-char ) + ps-encoded-char = "(a)" ; (@) + / "(p)" ; (%) + / "(b)" ; (!) + / "(q)" ; (") + / "(u)" ; (_) + / "(l)" ; "(" + / "(r)" ; ")" + / "(" 3DIGIT ")" + + The 822.3DIGIT in EBNF.ps-encoded-char must have range 0-127, and is + interpreted in decimal as the corresponding ASCII character. Special + encodings are given for: at sign (@), percent (%), exclamation + mark/bang (!), double quote ("), underscore (_), left bracket ((), + and right bracket ()). These characters, with the exception of round + brackets, are not included in PrintableString, but are common in RFC + 822 addresses. The abbreviations will ease specification of RFC 822 + addresses from an X.400 system. These special encodings shall be + interpreted in a case insensitive manner, but always generated in + lower case. + + A reversible mapping between PrintableString and ASCII can now be + defined. The reversibility means that some values of printable + string (containing round braces) cannot be generated from ASCII. + Therefore, this mapping must only be used in cases where the + printable strings may only be derived from ASCII (and will therefore + have a restricted domain). For example, in this specification, it is + only applied to a Domain Defined Attribute which will have been + generated by use of this specification and a value such as "(" would + not be possible. + + To encode ASCII as PrintableString, the EBNF.ps-encoded syntax is + used, with all EBNF.ps-restricted-char mapped directly. All other + 822.CHAR are encoded as EBNF.ps-encoded-char. + + To encode PrintableString as ASCII, parse PrintableString as + EBNF.ps-encoded, and then reverse the previous mapping. If the + PrintableString cannot be parsed, then the mapping is being applied + in to an inappropriate value, and an error shall be given to the + procedure doing the mapping. In some cases, it may be preferable to + pass the printable string through unaltered. + + + + + + + + + + +Hardcastle-Kille [Page 29] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + Some examples are now given. Note the arrows which indicate + asymmetrical mappings: + + PrintableString ASCII + + 'a demo.' <-> 'a demo.' + foo(a)bar <-> foo@bar + (q)(u)(p)(q) <-> "_%" + (a) <-> @ + (A) -> @ + (l)a(r) <-> (a) + (126) <-> ~ + ( -> ( + (l) <-> ( + +Chapter 4 - Addressing + + Addressing is probably the trickiest problem of an X.400 <-> RFC 822 + gateway. Therefore it is given a separate chapter. This chapter, as + a side effect, also defines a textual representation of an X.400 O/R + Address. + + Initially we consider an address in the (human) mail user sense of + "what is typed at the mailsystem to reference a mail user". A basic + RFC 822 address is defined by the EBNF EBNF.822-address: + + 822-address = [ route ] addr-spec + + In an 822-MTS protocol, the originator and each recipient are + considered to be defined by such a construct. In an RFC 822 header, + the EBNF.822-address is encapsulated in the 822.address syntax rule, + and there may also be associated comments. None of this extra + information has any semantics, other than to the end user. + + The basic X.400 O/R Address, used by the MTS for routing, is defined + by MTS.ORAddress. In IPMS, the MTS.ORAddress is encapsulated within + IPMS.ORDescriptor. + + It can be seen that RFC 822 822.address must be mapped with + IPMS.ORDescriptor, and that RFC 822 EBNF.822-address must be mapped + with MTS.ORAddress. + +4.1. A textual representation of MTS.ORAddress + + MTS.ORAddress is structured as a set of attribute value pairs. It is + clearly necessary to be able to encode this in ASCII for gatewaying + purposes. All components shall be encoded, in order to guarantee + return of error messages, and to optimise third party replies. + + + +Hardcastle-Kille [Page 30] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + +4.2. Basic Representation + + An O/R Address has a number of structured and unstructured + attributes. For each unstructured attribute, a key and an encoding + is specified. For structured attributes, the X.400 attribute is + mapped onto one or more attribute value pairs. For domain defined + attributes, each element of the sequence will be mapped onto a triple + (key and two values), with each value having the same encoding. The + attributes are as follows, with 1984 attributes given in the first + part of the table. For each attribute, a reference is given, + consisting of the relevant sections in X.402 / ISO 10021-2, and the + extension identifier for 88 only attributes: + + Attribute (Component) Key Enc Ref Id + +84/88 Attributes + +MTS.CountryName C P 18.3.3 +MTS.AdministrationDomainName ADMD P 18.3.1 +MTS.PrivateDomainName PRMD P 18.3.21 +MTS.NetworkAddress X121 N 18.3.7 +MTS.TerminalIdentifier T-ID P 18.3.23 +MTS.OrganizationName O P/T 18.3.9 +MTS.OrganizationalUnitNames.value OU P/T 18.3.10 +MTS.NumericUserIdentifier UA-ID N 18.3.8 +MTS.PersonalName PN P/T 18.3.12 +MTS.PersonalName.surname S P/T 18.3.12 +MTS.PersonalName.given-name G P/T 18.3.12 +MTS.PersonalName.initials I P/T 18.3.12 +MTS.PersonalName + .generation-qualifier GQ P/T 18.3.12 +MTS.DomainDefinedAttribute.value DD P/T 18.1 + +88 Attributes + +MTS.CommonName CN P/T 18.3.2 1 +MTS.TeletexCommonName CN P/T 18.3.2 2 +MTS.TeletexOrganizationName O P/T 18.3.9 3 +MTS.TeletexPersonalName PN P/T 18.3.12 4 +MTS.TeletexPersonalName.surname S P/T 18.3.12 4 +MTS.TeletexPersonalName.given-name G P/T 18.3.12 4 +MTS.TeletexPersonalName.initials I P/T 18.3.12 4 +MTS.TeletexPersonalName + .generation-qualifier GQ P/T 18.3.12 4 +MTS.TeletexOrganizationalUnitNames + .value OU P/T 18.3.10 5 +MTS.TeletexDomainDefinedAttribute + .value DD P/T 18.1 6 + + + +Hardcastle-Kille [Page 31] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + +MTS.PDSName PD-SERVICE P 18.3.11 7 +MTS.PhysicalDeliveryCountryName PD-C P 18.3.13 8 +MTS.PostalCode PD-CODE P 18.3.19 9 +MTS.PhysicalDeliveryOfficeName PD-OFFICE P/T 18.3.14 10 +MTS.PhysicalDeliveryOfficeNumber PD-OFFICE-NUM P/T 18.3.15 11 +MTS.ExtensionORAddressComponents PD-EXT-ADDRESS P/T 18.3.4 12 +MTS.PhysicalDeliveryPersonName PD-PN P/T 18.3.17 13 +MTS.PhysicalDeliveryOrganizationName PD-O P/T 18.3.16 14 +MTS.ExtensionPhysicalDelivery + AddressComponents PD-EXT-DELIVERY P/T 18.3.5 15 +MTS.UnformattedPostalAddress PD-ADDRESS P/T 18.3.25 16 +MTS.StreetAddress PD-STREET P/T 18.3.22 17 +MTS.PostOfficeBoxAddress PD-BOX P/T 18.3.18 18 +MTS.PosteRestanteAddress PD-RESTANTE P/T 18.3.20 19 +MTS.UniquePostalName PD-UNIQUE P/T 18.3.26 20 +MTS.LocalPostalAttributes PD-LOCAL P/T 18.3.6 21 +MTS.ExtendedNetworkAddress + .e163-4-address.number NET-NUM N 18.3.7 22 +MTS.ExtendedNetworkAddress + .e163-4-address.sub-address NET-SUB N 18.3.7 22 +MTS.ExtendedNetworkAddress + .psap-address NET-PSAP X 18.3.7 22 +MTS.TerminalType T-TY I 18.3.24 23 + + The following keys identify different EBNF encodings, which are + associated with the ASCII representation of MTS.ORAddress. + + Key Encoding + + P printablestring + N numericstring + T teletex-string + P/T teletex-and-or-ps + I labelled-integer + X presentation-address + + The BNF for presentation-address is taken from the specification "A + String Encoding of Presentation Address" [Kille89a]. + + In most cases, the EBNF encoding maps directly to the ASN.1 encoding + of the attribute. There are a few exceptions. In cases where an + attribute can be encoded as either a PrintableString or NumericString + (Country, ADMD, PRMD), either form is mapped into the BNF. When + generating ASN.1, the NumericString encoding shall be used if the + string contains only digits. + + There are a number of cases where the P/T (teletex-and-or-ps) + representation is used. Where the key maps to a single attribute, + + + +Hardcastle-Kille [Page 32] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + this choice is reflected in the encoding of the attribute (attributes + 10-21). For most of the 1984 attributes and common name, there is a + printablestring and a teletex variant. This pair of attributes is + mapped onto the single component here. This will give a clean + mapping for the common cases where only one form of the name is used. + + Recently, ISO has undertaken work to specify a string form of O/R + Address [CCITT/ISO91a]. This has specified a number of string + keywords for attributes. As RFC 1148 was an input to this work, many + of the keywords are the same. To increase compatability, the + following alternative values shall be recognised when mapping from + RFC 822 to X.400. These shall not be generated when mapping from + X.400 to RFC 822. + + Keyword Alternative + + ADMD A + PRMD P + GQ Q + X121 X.121 + UA-ID N-ID + PD-OFFICE-NUMBER PD-OFFICE NUMBER + + When mapping from RFC 822 to X.400, the keywords: OU1, OU2, OU3, and + OU4, shall be recognised. If these are present, no keyword OU + shall be present. These will be treated as ordered values of OU. + +4.2.1. Encoding of Personal Name + + Handling of Personal Name and Teletex Personal Name based purely on + the EBNF.standard-type syntax defined above is likely to be clumsy. + It seems desirable to utilise the "human" conventions for encoding + these components. A syntax is defined, which is designed to provide + a clean encoding for the common cases of O/R Address specification + where: + + 1. There is no generational qualifier + + 2. Initials contain only letters + + 3. Given Name does not contain full stop ("."), and is at least + two characters long. + + 4. Surname does not contain full stop in the first two + characters. + + 5 If Surname is the only component, it does not contain full + stop. + + + +Hardcastle-Kille [Page 33] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + The following EBNF is defined: + + encoded-pn = [ given "." ] *( initial "." ) surname + + given = 2*<ps-char not including "."> + + initial = ALPHA + + surname = printablestring + + This is used to map from any string containing only printable string + characters to an O/R address personal name. To map from a string to + O/R Address components, parse the string according to the EBNF. The + given name and surname are assigned directly. All EBNF.initial + tokens are concatenated without intervening full stops to generate + the initials component. + + For an O/R address which follows the above restrictions, a string is + derived in the natural manner. In this case, the mapping will be + reversible. + + For example: + + GivenName = "Marshall" + Surname = "Rose" + + Maps with "Marshall.Rose" + + Initials = "MT" + Surname = "Rose" + + Maps with "M.T.Rose" + + GivenName = "Marshall" + Initials = "MT" + Surname = "Rose" + + Maps with "Marshall.M.T.Rose" + + Note that X.400 suggest that Initials is used to encode ALL initials. + Therefore, the defined encoding is "natural" when either GivenName or + Initials, but not both, are present. The case where both are present + can be encoded, but this appears to be contrived! + +4.2.2. Standard Encoding of MTS.ORAddress + + Given this structure, we can specify a BNF representation of an O/R + Address. + + + +Hardcastle-Kille [Page 34] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + std-or-address = 1*( "/" attribute "=" value ) "/" + attribute = standard-type + / "RFC-822" + / registered-dd-type + / dd-key "." std-printablestring + standard-type = key-string + + registered-dd-type + = key-string + dd-key = key-string + + value = std-printablestring + + std-printablestring + = *( std-char / std-pair ) + std-char = <"{", "}", "*", and any ps-char + except "/" and "="> + std-pair = "$" ps-char + + The standard-type is any key defined in the table in Section 4.2, + except PN, and DD. The BNF leads to a set of attribute/value pairs. + The value is interpreted according to the EBNF encoding defined in + the table. + + If the standard-type is PN, the value is interpreted according to + EBNF.encoded-pn, and the components of MTS.PersonalName and/or + MTS.TeletexPersonalName derived accordingly. + + If dd-key is the recognised Domain Defined string (DD), then the type + and value are interpreted according to the syntax implied from the + encoding, and aligned to either the teletex or printable string form. + Key and value shall have the same encoding. + + If value is "RFC-822", then the (printable string) Domain Defined + Type of "RFC-822" is assumed. This is an optimised encoding of the + domain defined type defined by this specification. + + The matching of all keywords shall be done in a case-independent + manner. + + EBNF.std-or-address uses the characters "/" and "=" as delimiters. + Domain Defined Attributes and any value may contain these characters. + A quoting mechanism, using the non-printable string "$" is used to + allow these characters to be represented. + + If the value is registered-dd-type, and the value is registered at + the Internet Assigned Numbers Authority (IANA) as an accepted Domain + Defined Attribute type, then the value shall be interpreted + + + +Hardcastle-Kille [Page 35] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + accordingly. This restriction maximises the syntax checking which + can be done at a gateway. + +4.3. EBNF.822-address <-> MTS.ORAddress + + Ideally, the mapping specified would be entirely symmetrical and + global, to enable addresses to be referred to transparently in the + remote system, with the choice of gateway being left to the Message + Transfer Service. There are two fundamental reasons why this is not + possible: + + 1. The syntaxes are sufficiently different to make this + awkward. + + 2. In the general case, there would not be the necessary + administrative co-operation between the X.400 and RFC 822 + worlds, which would be needed for this to work. + + Therefore, an asymmetrical mapping is defined, which can be + symmetrical where there is appropriate administrative control. + +4.3.1. X.400 encoded in RFC 822 + + The std-or-address syntax is used to encode O/R Address information + in the 822.local-part of EBNF.822-address. In some cases, further + O/R Address information is associated with the 822.domain component. + This cannot be used in the general case, due to character set + problems, and to the variants of X.400 O/R Addresses which use + different attribute types. The only way to encode the full + PrintableString character set in a domain is by use of the + 822.domain-ref syntax (i.e. 822.atom). This is likely to cause + problems on many systems. The effective character set of domains is + in practice reduced from the RFC 822 set, by restrictions imposed by + domain conventions and policy, and by restrictions in RFC 821. + + A generic 822.address consists of a 822.local-part and a sequence of + 822.domains (e.g., <@domain1,@domain2:user@domain3>). All except the + 822.domain associated with the 822.local-part (domain3 in this case) + are considered to specify routing within the RFC 822 world, and will + not be interpreted by the gateway (although they may have identified + the gateway from within the RFC 822 world). + + The 822.domain associated with the 822.local-part identifies the + gateway from within the RFC 822 world. This final 822.domain may be + used to determine some number of O/R Address attributes, where this + does not conflict with the first role. RFC 822 routing to gateways + will usually be set up to facilitate the 822.domain being used for + both purposes. The following O/R Address attributes are considered + + + +Hardcastle-Kille [Page 36] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + as a hierarchy, and may be specified by the domain. They are (in + order of hierarchy): + + Country, ADMD, PRMD, Organisation, Organisational Unit + + There may be multiple Organisational Units. + + A global mapping is defined between domain specifications, and some + set of attributes. This association proceeds hierarchically. For + example, if a domain implies ADMD, it also implies country. + Subdomains under this are associated according to the O/R Address + hierarchy. For example: + + => "AC.UK" might be associated with + C="GB", ADMD="GOLD 400", PRMD="UK.AC" + + then domain "R-D.Salford.AC.UK" maps with + C="GB", ADMD="GOLD 400", PRMD="UK.AC", O="Salford", OU="R-D" + + There are three basic reasons why a domain/attribute mapping might be + maintained, as opposed to using simply subdomains: + + 1. As a shorthand to avoid redundant X.400 information. In + particular, there will often be only one ADMD per country, + and so it does not need to be given explicitly. + + 2. To deal with cases where attribute values do not fit the + syntax: + + domain-syntax = alphanum [ *alphanumhyphen alphanum ] + alphanum = <ALPHA or DIGIT> + alphanumhyphen = <ALPHA or DIGIT or HYPHEN> + + + Although RFC 822 allows for a more general syntax, this + restricted syntax is chosen as it is the one chosen by the + various domain service administrations. + + 3. To deal with missing elements in the hierarchy. A domain + may be associated with an omitted attribute in conjunction + with several present ones. When performing the algorithmic + insertion of components lower in the hierarchy, the omitted + value shall be skipped. For example, if "HNE.EGM" is + associated with "C=TC", "ADMD=ECQ", "PRMD=HNE", and omitted + organisation, then "ZI.HNE.EGM" is mapped with "C=TC", + "ADMD=ECQ", "PRMD=HNE", "OU=ZI". Attributes may have null + values, and this is treated separately from omitted + attributes (whilst it would be bad practice to treat these + + + +Hardcastle-Kille [Page 37] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + two cases differently, they must be allowed for). + + This set of mappings needs be known by the gateways relaying between + the RFC 822 world, and the O/R Address space associated with the + mapping in question. There needs to be a single global definition of + this set of mappings. A mapping implies an adminstrative equivalence + between the two parts of the namespaces which are mapped together. + To correctly route in all cases, it is necessary for all gateways to + know the mapping. To facilitate distribution of a global set of + mappings, a format for the exchange of this information is defined in + Appendix F. + + The remaining attributes are encoded on the LHS, using the EBNF.std- + or-address syntax. For example: + + /I=J/S=Linnimouth/GQ=5/@Marketing.Widget.COM + + encodes the MTS.ORAddress consisting of: + + MTS.CountryName = "TC" + MTS.AdministrationDomainName = "BTT" + MTS.OrganizationName = "Widget" + MTS.OrganizationalUnitNames.value = "Marketing" + MTS.PersonalName.surname = "Linnimouth" + MTS.PersonalName.initials = "J" + MTS.PersonalName.generation-qualifier = "5" + + The first three attributes are determined by the domain Widget.COM. + Then, the first element of OrganizationalUnitNames is determined + systematically, and the remaining attributes are encoded on the LHS. + In an extreme case, all of the attributes will be on the LHS. As the + domain cannot be null, the RHS will simply be a domain indicating the + gateway. + + The RHS (domain) encoding is designed to deal cleanly with common + addresses, and so the amount of information on the RHS is maximised. + In particular, it covers the Mnemonic O/R Address using a 1984 + compatible encoding. This is seen as the dominant form of O/R + Address. Use of other forms of O/R Address, and teletex encoded + attributes will require an LHS encoding. + + There is a further mechanism to simplify the encoding of common + cases, where the only attributes to be encoded on the LHS is a (non- + Teletex) Personal Name attributes which comply with the restrictions + of 4.2.1. To achieve this, the 822.local-part shall be encoded as + EBNF.encoded-pn. In the previous example, if the GenerationQualifier + was not present in the previous example O/R Address, it would map + with the RFC 822 address: J.Linnimouth@Marketing.Widget.COM. + + + +Hardcastle-Kille [Page 38] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + From the standpoint of the RFC 822 Message Transfer System, the + domain specification is simply used to route the message in the + standard manner. The standard domain mechanisms are used to select + appropriate gateways for the corresponding O/R Address space. In + most cases, this will be done by registering the higher levels, and + assuming that the gateway can handle the lower levels. + +4.3.2. RFC 822 encoded in X.400 + + In some cases, the encoding defined above may be reversed, to give a + "natural" encoding of genuine RFC 822 addresses. This depends + largely on the allocation of appropriate management domains. + + The general case is mapped by use of domain defined attributes. A + Domain defined type "RFC-822" is defined. The associated attribute + value is an ASCII string encoded according to Section 3.3.3 of this + specification. The interpretation of the ASCII string depends on the + context of the gateway. + + 1. In the context of RFC 822, and RFC 920 + [Crocker82a,Postel84a], the string can be used directly. + + 2. In the context of the JNT Mail protocol, and the NRS + [Kille84a,Larmouth83a], the string shall be interpreted + according to Mailgroup Note 15 [Kille84b]. + + 3. In the context of UUCP based systems, the string shall be + interpreted as defined in [Horton86a]. + + Other O/R Address attributes will be used to identify a context in + which the O/R Address will be interpreted. This might be a + Management Domain, or some part of a Management Domain which + identifies a gateway MTA. For example: + + C = "GB" + ADMD = "GOLD 400" + PRMD = "UK.AC" + O = "UCL" + OU = "CS" + "RFC-822" = "Jimmy(a)WIDGET-LABS.CO.UK" + + OR + + C = "TC" + ADMD = "Wizz.mail" + PRMD = "42" + "rfc-822" = "postel(a)venera.isi.edu" + + + + +Hardcastle-Kille [Page 39] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + Note in each case the PrintableString encoding of "@" as "(a)". In + the second example, the "RFC-822" domain defined attribute is + interpreted everywhere within the (Private) Management Domain. In + the first example, further attributes are needed within the + Management Domain to identify a gateway. Thus, this scheme can be + used with varying levels of Management Domain co-operation. + + There is a limit of 128 characters in the length of value of a domain + defined attribute, and an O/R Address can have a maxmimum of four + domain defined attributes. Where the printable string generated from + the RFC 822 address exceeeds this value, additional domain defined + attributes are used to enable up to 512 characters to be encoded. + These attributes shall be filled completely before the next one is + started. The DDA keywords are: RFC822C1; RFC822C2; RFC822C3. + Longer addresses cannot be encoded. + + There is, analagous with 4.3.1, a means to associate parts of the O/R + Address hierarchy with domains. There is an analogous global + mapping, which in most cases will be the inverse of the domain to O/R + address mapping. The mapping is maintained separately, as there may + be differences (e.g., two alternate domain names map to the same set + of O/R address components). + +4.3.3. Component Ordering + + In most cases, ordering of O/R Address components is not significant + for the mappings specified. However, Organisational Units (printable + string and teletex forms) and Domain Defined Attributes are specified + as SEQUENCE in MTS.ORAddress, and so their order may be significant. + This specification needs to take account of this: + + 1. To allow consistent mapping into the domain hierarchy + + 2. To ensure preservation of order over multiple mappings. + + There are three places where an order is specified: + + 1. The text encoding (std-or-address) of MTS.ORAddress as used + in the local-part of an RFC 822 address. An order is needed + for those components which may have multiple values + (Organisational Unit, and Domain Defined Attributes). When + generating an 822.std-or-address, components of a given type + shall be in hierarchical order with the most significant + component on the RHS. If there is an Organisation + Attribute, it shall be to the right of any Organisational + Unit attributes. These requirements are for the following + reasons: + + + + +Hardcastle-Kille [Page 40] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + - Alignment to the hierarchy of other components in RFC + 822 addresses (thus, Organisational Units will appear + in the same order, whether encoded on the RHS or LHS). + Note the differences of JNT Mail as described in + Appendix B. + + - Backwards compatibility with RFC 987/1026. + + - To ensure that gateways generate consistent addresses. + This is both to help end users, and to generate + identical message ids. + + Further, it is recommended that all other attributes are + generated according to this ordering, so that all attributes + so encoded follow a consistent hierarchy. When generating + 822.msg-id, this order shall be followed. + + 2. For the Organisational Units (OU) in MTS.ORAddress, the + first OU in the SEQUENCE is the most significant, as + specified in X.400. + + 3. For the Domain Defined Attributes in MTS.ORAddress, the + First Domain Defined Attribute in the SEQUENCE is the most + significant. + + Note that although this ordering is mandatory for this + mapping, there are NO implications on ordering significance + within X.400, where this is a Management Domain issue. + +4.3.4. RFC 822 -> X.400 + + There are two basic cases: + + 1. X.400 addresses encoded in RFC 822. This will also include + RFC 822 addresses which are given reversible encodings. + + 2. "Genuine" RFC 822 addresses. + + The mapping shall proceed as follows, by first assuming case 1). + +STAGE I. + + 1. If the 822-address is not of the form: + + local-part "@" domain + + take the domain which will be routed on and apply step 2 of + stage 1 to derive (a possibly null) set of attributes. Then + + + +Hardcastle-Kille [Page 41] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + go to stage II. + + NOTE:It may be appropriate to reduce a source route address + to this form by removal of all bar the last domain. In + terms of the design intentions of RFC 822, this would + be an incorrect action. However, in most real cases, + it will do the "right" thing and provide a better + service to the end user. This is a reflection on the + excessive and inappropriate use of source routing in + RFC 822 based systems. Either approach, or the + intermediate approach of stripping only domain + references which reference the local gateway are + conformant to this specification. + + 2. Attempt to parse EBNF.domain as: + + *( domain-syntax "." ) known-domain + + Where EBNF.known-domain is the longest possible match in the + set of globally defined mappings (see Appendix F). If this + fails, and the EBNF.domain does not explicitly identify the + local gateway, go to stage II. If the domain explicitly + identifies the gateway, allocate no attributes. Otherwise, + allocate the attributes associated with EBNF.known-domain. + For each component, systematically allocate the attribute + implied by each EBNF.domain-syntax component in the order: + C, ADMD, PRMD, O, OU. Note that if the mapping used + identifies an "omitted attribute", then this attribute + should be omitted in the systematic allocation. If this new + component exceed an upper bound (ADMD: 16; PRMD: 16; O: 64; + OU: 32) or it would lead to more than four OUs, then go to + stage II with the attributes derived. + + At this stage, a set of attributes has been derived, which + will give appropriate routing within X.400. If any of the + later steps of Stage I force use of Stage II, then these + attributes should be used in Stage II. + + 3. If the 822.local-part uses the 822.quoted-string encoding, + remove this quoting. If this unquoted 822.local-part has + leading space, trailing space, or two adjacent space go to + stage II. + + 4. If the unquoted 822.local-part contains any characters not + in PrintableString, go to stage II. + + 5. Parse the (unquoted) 822.local-part according to the EBNF + EBNF.std-or-address. Checking of upper bounds should not be + + + +Hardcastle-Kille [Page 42] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + done at this point. If this parse fails, parse the local- + part according to the EBNF EBNF.encoded-pn. If this parse + fails, go to stage II. The result is a set of type/value + pairs. If the set of attributes leads to an address of any + form other than mnemonic form, then only these attributes + should be taken. If (for mnemonic form) the values generated + conflict with those derived in step 2 (e.g., a duplicated + country attribute), the domain is assumed to be a remote + gateway. In this case, take only the LHS derived + attributes, together with any RHS dericed attributes which + are more significant thant the most signicant attribute + which is duplicated (e.g., if there is a duplicate PRMD, but + no LHS derived ADMD and country, then the ADMD and country + should be taken from the RHS). therwise add LHS and RHS + derived attributes together. + + 6. Associate the EBNF.attribute-value syntax (determined from + the identified type) with each value, and check that it + conforms. If not, go to stage II. + + 7. Ensure that the set of attributes conforms both to the + MTS.ORAddress specification and to the restrictions on this + set given in X.400, and that no upper bounds are exceeded + for any attribute. If not go to stage II. + + 8. Build the O/R Address from this information. + +STAGE II. + + This will only be reached if the RFC 822 EBNF.822-address is not a + valid X.400 encoding. This implies that the address must refer to a + recipient on an RFC 822 system. Such addresses shall be encoded in + an X.400 O/R Address using a domain defined attribute. + + 1. Convert the EBNF.822-address to PrintableString, as + specified in Chapter 3. + + 2. Generate the "RFC-822" domain defined attribute from this + string. + + 3. Build the rest of the O/R Address in the manner described + below. + + It may not be possible to encode the domain defined attribute due to + length restrictions. If the limit is exceeded by a mapping at the + MTS level, then the gateway shall reject the message in question. If + this occurs at the IPMS level, then the action will depend on the + policy being taken for IPMS encoding, which is discussed in Section + + + +Hardcastle-Kille [Page 43] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + 5.1.3. + + If Stage I has identified a set of attributes, use these to build the + remainder of the address. The administrative equivalence of the + mappings will ensure correct routing throug X.400 to a gateway back + to RFC 822. + + If Stage I has not identified a set of attributes, the remainder of + the O/R address effectively identifies a source route to a gateway + from the X.400 side. There are three cases, which are handled + differently: + + 822-MTS Return Address + This shall be set up so that errors are returned through the + same gateway. Therefore, the O/R Address of the local + gateway shall be used. + + IPMS Addresses + These are optimised for replying. In general, the message + may end up anywhere within the X.400 world, and so this + optimisation identifies a gateway appropriate for the RFC + 822 address being converted. The 822.domain to which the + address would be routed is used to select an appropriate + gateway. A globally defined set of mappings is used, which + identifies (the O/R Address components of) appropriate + gateways for parts of the domain namespace. The longest + possible match on the 822.domain defines which gateway to + use. The table format for distribution of this information + is defined in Appendix F. + + This global mapping is used for parts of the RFC 822 + namespace which do not have an administrative equivalence + with any part of the X.400 namespace, but for which it is + desirable to identify a preferred X.400 gateway in order to + optimise routing. + + If no mapping is found for the 822.domain, a default value + (typically that of the local gateway) is used. It is never + appropriate to ignore the globally defined mappings. In + some cases, it may be appropriate to locally override the + globally defined mappings (e.g., to identify a gateway close + to a recipient of the message). This is likely to be where + the global mapping identifies a public gateway, and the + local gateway has an agreement with a private gateway which + it prefers to use. + + 822-MTS Recipient + As the RFC 822 and X.400 worlds are fully connected, there + + + +Hardcastle-Kille [Page 44] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + is no technical reason for this situation to occur. In some + cases, routing may be configured to connect two parts of the + RFC 822 world using X.400. The information that this part + of the domain space should be routed by X.400 rather than + remaining within the RFC 822 world will be configured + privately into the gateway in question. The O/R address + shall then be generated in the same manner as for an IPMS + address, using the globally defined mappings. It is to + support this case that the definition of the global domain + to gateway mapping is important, as the use of this mapping + will lead to a remote X.400 address, which can be routed by + X.400 routing procedures. The information in this mapping + shall not be used as a basis for deciding to convert a + message from RFC 822 to X.400. + +4.3.4.1. Heuristics for mapping RFC 822 to X.400 + + RFC 822 users will often use an LHS encoded address to identify an + X.400 recipient. Because the syntax is fairly complex, a number of + heuristics may be applied to facilitate this form of usage. A + gateway should take care not to be overly "clever" with heuristics, + as this may cause more confusion than a more mechanical approach. + The heuristics are as follows: + + 1. Ignore the omission of a trailing "/" in the std-or syntax. + + 2. If there is no ADMD component, and both country and PRMD are + present, the value of /ADMD= / (single space) is assumed. + + 3. Parse the unquoted local part according to the EBNF colon- + or-address. This may facilitate users used to this + delimiter. + + colon-or-address = 1*(attribute "=" value ";" *(LWSP-char)) + + The remaining heuristic relates to ordering of address components. + The ordering of attributes may be inverted or mixed. For this + reason, the following heuristics may be applied: + + 4. If there is an Organisation attribute to the left of any Org + Unit attribute, assume that the hierarchy is inverted. + +4.3.5. X.400 -> RFC 822 + + There are two basic cases: + + 1. RFC 822 addresses encoded in X.400. + + + + +Hardcastle-Kille [Page 45] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + 2. "Genuine" X.400 addresses. This may include symmetrically + encoded RFC 822 addresses. + + When a MTS Recipient O/R Address is interpreted, gatewaying will be + selected if there is a single "RFC-822" domain defined attribute + present and the local gateway is identified by the remainder of the + O/R Address. In this case, use mapping A. For other O/R Addresses + which + + 1. Contain the special attribute. + + AND + + 2. Identifies the local gateway or any other known gateway with + the other attributes. + + use mapping A. In other cases, use mapping B. + + NOTE: + A pragmatic approach would be to assume that any O/R + Address with the special domain defined attribute identifies + an RFC 822 address. This will usually work correctly, but is + in principle not correct. Use of this approach is + conformant to this specification. + +Mapping A + + 1. Map the domain defined attribute value to ASCII, as defined + in Chapter 3. + +Mapping B + + This is used for X.400 addresses which do not use the explicit RFC + 822 encoding. + + 1. For all string encoded attributes, remove any leading or + trailing spaces, and replace adjacent spaces with a single + space. + + The only attribute which is permitted to have zero length is + the ADMD. This should be mapped onto a single space. + + These transformations are for lookup only. If an + EBNF.std-or-address mapping is used as in 4), then the + orginal values should be used. + + 2. Map numeric country codes to the two letter values. + + + + +Hardcastle-Kille [Page 46] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + 3. Noting the hierarchy specified in 4.3.1 and including + omitted attributes, determine the maximum set of attributes + which have an associated domain specification in the + globally defined mapping. If no match is found, allocate + the domain as the domain specification of the local gateway, + and go to step 5. + + Note: It might be appropriate to use a non-local domain. + This would be selected by a global mapping analagous to + the one described at the end of 4.3.4. This is not + done, primarily because use of RFC 822 to connect X.400 + systems is not expected to be significant. + + In cases where the address refers to an X.400 UA, it is + important that the generated domain will correctly route to + a gateway. In general, this is achieved by carefully co- + ordinating RFC 822 routing with the definition of the global + mappings, as there is no easy way for the gateway to make + this check. One rule that shall be used is that domains + with only one component will not route to a gateway. If the + generated domain does not route correctly, the address is + treated as if no match is found. + + 4. The mapping identified in 3) gives a domain, and an O/R + address prefix. Follow the hierarchy: C, ADMD, PRMD, O, OU. + For each successive component below the O/R address prefix, + which conforms to the syntax EBNF.domain-syntax (as defined + in 4.3.1), allocate the next subdomain. At least one + attribute of the X.400 address shall not be mapped onto + subdomain, as 822.local-part cannot be null. If there are + omitted attributes in the O/R address prefix, these will + have correctly and uniquely mapped to a domain component. + Where there is an attribute omitted below the prefix, all + attributes remaining in the O/R address shall be encoded on + the LHS. This is to ensure a reversible mapping. For + example, if the is an addres /S=XX/O=YY/ADMD=A/C=NN/ and a + mapping for /ADMD=A/C=NN/ is used, then /S=XX/O=YY/ is + encoded on the LHS. + + 5. If the address is not mnemonic form (form 1 variant 1), + then all of the attributes in the address should be encoded + on the LHS in EBNF.std-or-address syntax, as described + below. + + For addresses of mnemonic form, if the remaining components + are personal-name components, conforming to the restrictions + of 4.2.1, then EBNF.encoded-pn is derived to form + 822.local-part. In other cases the remaining components are + + + +Hardcastle-Kille [Page 47] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + simply encoded as 822.local-part using the + EBNF.std-or-address syntax. If necessary, the + 822.quoted-string encoding is used. The following are + examples of legal quoting: "a b".c@x; "a b.c"@x. Either + form may be generated, but the latter is preferred. + + If the derived 822.local-part can only be encoded by use of + 822.quoted-string, then use of the mapping defined + in [Kille89b] may be appropriate. Use of this mapping is + discouraged. + +4.4. Repeated Mappings + + There are two types of repeated mapping: + + 1. A recursive mapping, where the repeat is within one gateway + + 2 A source route, where the repetition occurs across multiple + gateways + +4.4.1. Recursive Mappings + + It is possible to supply an address which is recurive at a single + gateway. For example: + + C = "XX" + ADMD = "YY" + O = "ZZ" + "RFC-822" = "Smith(a)ZZ.YY.XX" + + This is mapped first to an RFC 822 address, and then back to the + X.400 address: + + C = "XX" + ADMD = "YY" + O = "ZZ" + Surname = "Smith" + + In some situations this type of recursion may be frequent. It is + important that where this occurs, that no unnecessary protocol + conversion occurs. This will minimise loss of service. + +4.4.2. Source Routes + + The mappings defined are symmetrical and reversible across a single + gateway. The symmetry is particularly useful in cases of (mail + exploder type) distribution list expansion. For example, an X.400 + user sends to a list on an RFC 822 system which he belongs to. The + + + +Hardcastle-Kille [Page 48] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + received message will have the originator and any 3rd party X.400 O/R + Addresses in correct format (rather than doubly encoded). In cases + (X.400 or RFC 822) where there is common agreement on gateway + identification, then this will apply to multiple gateways. + + When a message traverses multiple gateways, the mapping will always + be reversible, in that a reply can be generated which will correctly + reverse the path. In many cases, the mapping will also be + symmetrical, which will appear clean to the end user. For example, + if countries "AB" and "XY" have RFC 822 networks, but are + interconnected by X.400, the following may happen: The originator + specifies: + + Joe.Soap@Widget.PTT.XY + + This is routed to a gateway, which generates: + + C = "XY" + ADMD = "PTT" + PRMD = "Griddle MHS Providers" + Organisation = "Widget Corporation" + Surname = "Soap" + Given Name = "Joe" + + This is then routed to another gateway where the mapping is reversed + to give: + + Joe.Soap@Widget.PTT.XY + + Here, use of the gateway is transparent. + + Mappings will only be symmetrical where mapping tables are defined. + In other cases, the reversibility is more important, due to the (far + too frequent) cases where RFC 822 and X.400 services are partitioned. + + The syntax may be used to source route. THIS IS STRONGLY + DISCOURAGED. For example: + + X.400 -> RFC 822 -> X.400 + + C = "UK" + ADMD = "Gold 400" + PRMD = "UK.AC" + "RFC-822" = "/PN=Duval/DD.Title=Manager/(a)Inria.ATLAS.FR" + + This will be sent to an arbitrary UK Academic Community gateway by + X.400. Then it will be sent by JNT Mail to another gateway + determined by the domain Inria.ATLAS.FR (FR.ATLAS.Inria). This will + + + +Hardcastle-Kille [Page 49] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + then derive the X.400 O/R Address: + + C = "FR" + ADMD = "ATLAS" + PRMD = "Inria" + PN.S = "Duval" + "Title" = "Manager" + + Similarly: + RFC 822 -> X.400 -> RFC 822 + +"/C=UK/ADMD=BT/PRMD=AC/RFC-822=jj(a)seismo.css.gov/"@monet.berkeley.edu + + This will be sent to monet.berkeley.edu by RFC 822, then to the AC + PRMD by X.400, and then to jj@seismo.css.gov by RFC 822. + +4.5. Directory Names + + Directory Names are an optional part of O/R Name, along with O/R + Address. The RFC 822 addresses are mapped onto the O/R Address + component. As there is no functional mapping for the Directory Name + on the RFC 822 side, a textual mapping is used. There is no + requirement for reversibility in terms of the goals of this + specification. There may be some loss of functionality in terms of + third party recipients where only a directory name is given, but this + seems preferable to the significant extra complexity of adding a full + mapping for Directory Names. + + Note:There is ongoing work on specification of a "user friendly" + format for directory names. If this is adopted as an + internet standard, it will be recommended, but not required, + for use here. + +4.6. MTS Mappings + + The basic mappings at the MTS level are: + + 1) 822-MTS originator -> + MTS.PerMessageSubmissionFields.originator-name + MTS.OtherMessageDeliveryFields.originator-name -> + 822-MTS originator + + 2) 822-MTS recipient -> + MTS.PerRecipientMessageSubmissionFields + MTS.OtherMessageDeliveryFields.this-recipient-name -> + 822-MTS recipient + + 822-MTS recipients and return addresses are encoded as EBNF.822- + + + +Hardcastle-Kille [Page 50] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + address. + + The MTS Originator is always encoded as MTS.OriginatorName, which + maps onto MTS.ORAddressAndOptionalDirectoryName, which in turn maps + onto MTS.ORName. + +4.6.1. RFC 822 -> X.400 + + From the 822-MTS Originator, use the basic ORAddress mapping, to + generate MTS.PerMessageSubmissionFields.originator-name (MTS.ORName), + without a DirectoryName. + + For recipients, the following settings are made for each component of + MTS.PerRecipientMessageSubmissionFields. + + recipient-name + This is derived from the 822-MTS recipient by the basic + ORAddress mapping. + + originator-report-request + This is be set according to content return policy, as + discussed in Section 5.2. + + explicit-conversion + This optional component is omitted, as this service is not + needed + + extensions + The default value (no extensions) is used + +4.6.2. X.400 -> RFC 822 + + The basic functionality is to generate the 822-MTS originator and + recipients. There is information present on the X.400 side, which + cannot be mapped into analogous 822-MTS services. For this reason, + new RFC 822 fields are added for the MTS Originator and Recipients. + The information discarded at the 822-MTS level will be present in + these fields. In some cases a (positive) delivery report will be + generated. + +4.6.2.1. 822-MTS Mappings + + Use the basic ORAddress mapping, to generate the 822-MTS originator + (return address) from MTS.OtherMessageDeliveryFields.originator-name + (MTS.ORName). If MTS.ORName.directory-name is present, it is + discarded. (Note that it will be presented to the user, as described + in 4.6.2.2). + + + + +Hardcastle-Kille [Page 51] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + The 822-MTS recipient is conceptually generated from + MTS.OtherMessageDeliveryFields.this-recipient-name. This is done by + taking MTS.OtherMessageDeliveryFields.this-recipient-name, and + generating an 822-MTS recipient according to the basic ORAddress + mapping, discarding MTS.ORName.directory-name if present. However, + if this model was followed exactly, there would be no possibility to + have multiple 822-MTS recipients on a single message. This is + unacceptable, and so layering is violated. The mapping needs to use + the MTA level information, and map each value of + MTA.PerRecipientMessageTransferFields.recipient-name, where the + responsibility bit is set, onto an 822-MTS recipient. + +4.6.2.2. Generation of RFC 822 Headers + + Not all per-recipient information can be passed at the 822-MTS level. + For this reason, two new RFC 822 headers are created, in order to + carry this information to the RFC 822 recipient. These fields are + "X400-Originator:" and "X400-Recipients:". + + The "X400-Originator:" field is set to the same value as the 822-MTS + originator. In addition, if + MTS.OtherMessageDeliveryFields.originator-name (MTS.ORName) contains + MTS.ORName.directory-name then this Directory Name shall be + represented in an 822.comment. + + Recipient names, taken from each value of + MTS.OtherMessageDeliveryFields.this-recipient-name and + MTS.OtherMessageDeliveryFields.other-recipient-names are made + available to the RFC 822 user by use of the "X400-Recipients:" field. + By taking the recipients at the MTS level, disclosure of recipients + will be dealt with correctly. However, this conflicts with a desire + to optimise mail transfer. There is no problem when disclosure of + recipients is allowed. Similarly, there is no problem if there is + only one RFC 822 recipient, as the "X400-Recipients field is only + given one address. + + There is a problem if there are multiple RFC 822 recipients, and + disclosure of recipients is prohibited. Two options are allowed: + + 1. Generate one copy of the message for each RFC 822 recipient, + with the "X400-Recipients field correctly set to the + recipient of that copy. This is functionally correct, but + is likely to be more expensive. + + 2. Discard the per-recipient information, and insert a field: + + X400-Recipients: non-disclosure:; + + + + +Hardcastle-Kille [Page 52] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + This is the recommended option. + + A third option of ignoring the disclosure flag is not allowed. If + any MTS.ORName.directory-name is present, it shall be represented in + an 822.comment. + + If MTS.OtherMessageDeliveryFields.orignally-intended-recipient-name + is present, then there has been redirection, or there has been + distribution list expansion. Distribution list expansion is a per- + message option, and the information associated with this is + represented by the "DL-Expansion-History:" field descrined in Section + 5.3.6. Other information is represented in an 822.comment associated + associated with MTS.OtherMessageDeliveryFields.this-recipient-name, + The message may be delivered to different RFC 822 recipients, and so + several addresses in the "X400-Recipients:" field may have such + comments. The non-commented recipient is the RFC 822 recipient. The + EBNF of the comment is: + + + redirect-comment = + [ "Originally To:" ] mailbox "Redirected" + [ "Again" ] "on" date-time + "To:" redirection-reason + + redirection-reason = + "Recipient Assigned Alternate Recipient" + / "Originator Requested Alternate Recipient" + / "Recipient MD Assigned Alternate Recipient" + + It is derived from + MTA.PerRecipientMessageTransferFields.extension.redirection-history. + An example of this is: + + X400-Recipients: postmaster@widget.com (Originally To: + sales-manager@sales.widget.com Redirected + on Thu, 30 May 91 14:39:40 +0100 To: Originator Assigned + Alternate Recipient postmaster@sales.widget.com Redirected + Again on Thu, 30 May 91 14:41:20 +0100 To: Recipient MD + Assigned Alternate Recipient) + + In addition, the following per-recipient services from + MTS.OtherMessageDeliveryFields.extensions are represented in comments + if they are used. None of these services can be provided on RFC 822 + networks, and so in general these will be informative strings + associated with other MTS recipients. In some cases, string values + are defined. For the remainder, the string value shall be chosen by + the implementor. If the parameter has a default value, then no + comment shall be inserted when the parameter has that default value. + + + +Hardcastle-Kille [Page 53] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + requested-delivery-method + + physical-forwarding-prohibited + "(Physical Forwarding Prohibited)". + + physical-forwarding-address-request + "(Physical Forwarding Address Requested)". + + physical-delivery-modes + + registered-mail-type + + recipient-number-for-advice + + physical-rendition-attributes + + physical-delivery-report-request + "(Physical Delivery Report Requested)". + + proof-of-delivery-request + "(Proof of Delivery Requested)". + +4.6.2.3. Delivery Report Generation + + If MTA.PerRecipientMessageTransferFields.per-recipient-indicators + requires a positive delivery notification, this shall be generated by + the gateway. Supplementary Information shall be set to indicate that + the report is gateway generated. This information shall include the + name of the gateway generating the report. + +4.6.3. Message IDs (MTS) + + A mapping from 822.msg-id to MTS.MTSIdentifier is defined. The + reverse mapping is not needed, as MTS.MTSIdentifier is always mapped + onto new RFC 822 fields. The value of MTS.MTSIdentifier.local-part + will facilitate correlation of gateway errors. + + To map from 822.msg-id, apply the standard mapping to 822.msg-id, in + order to generate an MTS.ORAddress. The Country, ADMD, and PRMD + components of this are used to generate MTS.MTSIdentifier.global- + domain-identifier. MTS.MTSIdentifier.local-identifier is set to the + 822.msg-id, including the braces "<" and ">". If this string is + longer than MTS.ub-local-id-length (32), then it is truncated to this + length. + + The reverse mapping is not used in this specification. It would be + applicable where MTS.MTSIdentifier.local-identifier is of syntax + 822.msg-id, and it algorithmically identifies MTS.MTSIdentifier. + + + +Hardcastle-Kille [Page 54] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + +4.7. IPMS Mappings + + All RFC 822 addresses are assumed to use the 822.mailbox syntax. + This includes all 822.comments associated with the lexical tokens of + the 822.mailbox. In the IPMS O/R Names are encoded as MTS.ORName. + This is used within the IPMS.ORDescriptor, IPMS.RecipientSpecifier, + and IPMS.IPMIdentifier. An asymmetrical mapping is defined between + these components. + +4.7.1. RFC 822 -> X.400 + + To derive IPMS.ORDescriptor from an RFC 822 address. + + 1. Take the address, and extract an EBNF.822-address. This can + be derived trivially from either the 822.addr-spec or + 822.route-addr syntax. This is mapped to MTS.ORName as + described above, and used as IMPS.ORDescriptor.formal-name. + + 2. A string shall be built consisting of (if present): + + - The 822.phrase component if the 822.address is an + 822.phrase 822.route-addr construct. + + - Any 822.comments, in order, retaining the parentheses. + + This string is then encoded into T.61 use a human oriented + mapping (as described in Chapter 3). If the string is not + null, it is assigned to IPMS.ORDescriptor.free-form-name. + + 3. IPMS.ORDescriptor.telephone-number is omitted. + + If IPMS.ORDescriptor is being used in IPMS.RecipientSpecifier, + IPMS.RecipientSpecifier.reply-request and + IPMS.RecipientSpecifier.notification-requests are set to default + values (none and false). + + If the 822.group construct is present, any included 822.mailbox is + encoded as above to generate a separate IPMS.ORDescriptor. The + 822.group is mapped to T.61, and a IPMS.ORDescriptor with only an + free-form-name component built from it. + +4.7.2. X.400 -> RFC 822 + + Mapping from IPMS.ORDescriptor to RFC 822 address. In the basic + case, where IPMS.ORDescriptor.formal-name is present, proceed as + follows. + + 1. Encode IPMS.ORDescriptor.formal-name (MTS.ORName) as + + + +Hardcastle-Kille [Page 55] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + EBNF.822-address. + + 2a. If IPMS.ORDescriptor.free-form-name is present, convert it + to ASCII (Chapter 3), and use this as the 822.phrase + component of 822.mailbox using the 822.phrase 822.route-addr + construct. + + 2b. If IPMS.ORDescriptor.free-form-name is absent. If + EBNF.822-address is parsed as 822.addr-spec use this as the + encoding of 822.mailbox. If EBNF.822-address is parsed as + 822.route 822.addr-spec, then a 822.phrase taken from + 822.local-part is added. + + 3. If IPMS.ORDescriptor.telephone-number is present, this is + placed in an 822.comment, with the string "Tel ". The + normal international form of number is used. For example: + + (Tel +44-1-387-7050) + + 4. If IPMS.ORDescriptor.formal-name.directory-name is present, + then a text representation is placed in a trailing + 822.comment. + + 5. If IPMS.RecipientSpecifier.report-request has any non- + default values, then an 822.comment "(Receipt Notification + Requested)", and/or "(Non Receipt Notification Requested)", + and/or "(IPM Return Requested)" is appended to the address. + If both receipt and non-receipt notfications are requested, + the comment relating to the latter may be omitted, to make + the RFC 822 address cleaner. The effort of correlating P1 + and P2 information is too great to justify the gateway + sending Receipt Notifications. + + 6. If IPMS.RecipientSpecifier.reply-request is True, an + 822.comment "(Reply requested)" is appended to the address. + + If IPMS.ORDescriptor.formal-name is absent, IPMS.ORDescriptor.free- + form-name is converted to ASCII, and used as 822.phrase within the + RFC 822 822.group syntax. For example: + + Free Form Name ":" ";" + + Steps 3-6 are then followed. + +4.7.3. IP Message IDs + + There is a need to map both ways between 822.msg-id and + IPMS.IPMIdentifier. This allows for X.400 Receipt Notifications, + + + +Hardcastle-Kille [Page 56] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + Replies, and Cross References to reference an RFC 822 Message ID, + which is preferable to a gateway generated ID. A reversible and + symmetrical mapping is defined. This allows for good things to + happen when messages pass multiple times across the X.400/RFC 822 + boundary. + + An important issue with messages identifiers is mapping to the exact + form, as many systems use these ids as uninterpreted keys. The use + of table driven mappings is not always symmetrical, particularly in + the light of alternative domain names, and alternative management + domains. For this reason, a purely algorithmic mapping is used. A + mapping which is simpler than that for addresses can be used for two + reasons: + + - There is no major requirement to make message IDs "natural" + + - There is no issue about being able to reply to message IDs. + (For addresses, creating a return path which works is more + important than being symmetrical). + + The mapping works by defining a way in which message IDs generated on + one side of the gateway can be represented on the other side in a + systematic manner. The mapping is defined so that the possibility of + clashes is is low enough to be treated as impossible. + +4.7.3.1. 822.msg-id represented in X.400 + + IPMS.IPMIdentifier.user is omitted. The IPMS.IPMIdentifier.user- + relative-identifier is set to a printable string encoding of the + 822.msg-id with the angle braces ("<" and ">") removed. The upper + bound on this component is 64. The options for handling this are + discussed in Section 5.1.3. + +4.7.3.2. IPMS.IPMIdentifier represented in RFC 822 + + The 822.domain of 822.msg-id is set to the value "MHS". The + 822.local-part of 822.msg-id is built as + + [ printablestring ] "*" [ std-or-address ] + + with EBNF.printablestring being the IPMS.IPMIdentifier.user- + relative-identifier, and std-or-address being an encoding of the + IPMS.IPMIdentifier.user. If necessary, the 822.quoted-string + encoding is used. For example: + + <"147*/S=Dietrich/O=Siemens/ADMD=DBP/C=DE/"@MHS> + + + + + +Hardcastle-Kille [Page 57] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + +4.7.3.3. 822.msg-id -> IPMS.IPMIdentifier + + If the 822.local-part can be parsed as: + + [ printablestring ] "*" [ std-or-address ] + + and the 822.domain is "MHS", then this ID was X.400 generated. If + EBNF.printablestring is present, the value is assigned to + IPMS.IPMIdentifier.user-relative-identifier. If EBNF.std-or-address + is present, the O/R Address components derived from it are used to + set IPMS.IPMIdentifier.user. + + Otherwise, this is an RFC 822 generated ID. In this case, set + IPMS.IPMIdentifier.user-relative-identifier to a printable string + encoding of the 822.msg-id without the angle braces. + +4.7.3.4. IPMS.IPMIdentifier -> 822.msg-id + + If IPMS.IPMIdentifier.user is absent, and IPMS.IPMIdentifier.user- + relative-identifier mapped to ASCII and angle braces added parses as + 822.msg-id, then this is an RFC 822 generated ID. + + Otherwise, the ID is X.400 generated. Use the + IPMS.IPMIdentifier.user to generate an EBNF.std-or-address form + string. Build the 822.local-part of the 822.msg-id with the syntax: + + [ printablestring ] "*" [ std-or-address ] + + The printablestring is taken from IPMS.IPMIdentifier.user-relative- + identifier. Use 822.quoted-string if necessary. The 822.msg-id is + generated with this 822.local-part, and "MHS" as the 822.domain. + +4.7.3.5. Phrase form + + In "InReply-To:" and "References:", the encoding 822.phrase may be + used as an alternative to 822.msg-id. To map from 822.phrase to + IPMS.IPMIdentifier, assign IPMS.IPMIdentifier.user-relative- + identifier to the phrase. When mapping from IPMS.IPMIdentifier for + "In-Reply-To:" and "References:", if IPMS.IPMIdentifier.user is + absent and IPMS.IPMIdentifier.user-relative-identifier does not parse + as 822.msg-id, generate an 822.phrase rather than adding the domain + MHS. + +4.7.3.6. RFC 987 backwards compatibility + + The mapping defined here is different to that used in RFC 987, as the + RFC 987 mapping lead to changed message IDs in many cases. Fixing + the problems is preferable to retaining backwards compatibility. An + + + +Hardcastle-Kille [Page 58] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + implementation of this standard is encouraged to recognise message + IDs generated by RFC 987. This is not required. + + RFC 987 generated encodings may be recognised as follows. When + mapping from X.400 to RFC 822, if the IPMS.IPMIdentifier.user- + relative-identifier is "RFC-822" the id is RFC 987 generated. When + mapping from RFC 822 to X.400, if the 822.domain is not "MHS", and + the 822.local-part can be parsed as + + [ printablestring ] "*" [ std-or-address ] + + then it is RFC 987 generated. In each of these cases, it is + recommended to follow the RFC 987 rules. + +Chapter 5 - Detailed Mappings + + This chapter specifies detailed mappings for the functions outlined + in Chapters 1 and 2. It makes extensive use of the notations and + mappings defined in Chapters 3 and 4. + +5.1. RFC 822 -> X.400 + +5.1.1. Basic Approach + + A single IP Message is generated from an RFC 822 message The RFC 822 + headers are used to generate the IPMS.Heading. The IP Message will + have one IA5 IPMS.BodyPart containing the RFC 822 message body. + + Some RFC 822 fields cannot be mapped onto a standard IPM Heading + field, and so an extended field is defined in Section 5.1.2. This is + then used for fields which cannot be mapped onto existing services. + + The message is submitted to the MTS, and the services required can be + defined by specifying MTS.MessageSubmissionEnvelope. A few + parameters of the MTA Abstract service are also specified, which are + not in principle available to the MTS User. Use of these services + allows RFC 822 MTA level parameters to be carried in the analogous + X.400 service elements. The advantages of this mapping far outweigh + the layering violation. + +5.1.2. X.400 Extension Field + + An IPMS Extension is defined: + + rfc-822-field HEADING-EXTENSION + VALUE RFC822FieldList + ::= id-rfc-822-field-list + + + + +Hardcastle-Kille [Page 59] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + RFC822FieldList ::= SEQUENCE OF RFC822Field + + RFC822Field ::= IA5String + + The Object Identifier id-rfc-822-field-list is defined in Appendix D. + + To encode any RFC 822 Header using this extension, an RFC822Field + element is built using the 822.field omitting the trailing CRLF + (e.g., "Fruit-Of-The-Day: Kiwi Fruit"). Structured fields shall be + unfolded. There shall be no space before the ":". The reverse + mapping builds the RFC 822 field in a straightforward manner. This + RFC822Field is appended to the RFC822FieldList, which is added to the + IPM Heading as an extension field. + +5.1.3. Generating the IPM + + The IPM (IPMS Service Request) is generated according to the rules of + this section. The IPMS.IPM.body usually consists of one IPMS.BodyPart + of type IPMS.IA5TextBodyPart with + IPMS.IA5TextBodyPart.parameters.repertoire set to the default (ia5) + which contains the body of the RFC 822 message. The exception is + where there is a "Comments:" field in the RFC 822 header. + + If no specific 1988 features are used, the IPM generated is encoded + as content type 2. Otherwise, it is encoded as content type 22. The + latter will always be the case if extension heading fields are + generated. + + When generating the IPM, the issue of upper bounds must be + considered. At the MTS and MTA level, this specification is strict + about enforcing upper bounds. Three options are available at the IPM + level. Use of any of these options conforms to this standard. + + 1. Ignore upper bounds, and generate messages in the natural + manner. This assumes that if any truncation is done, it + will happen at the recipient UA. This will maximise + transfer of information, but is likely break some recipient + UAs. + + 2. Reject any inbound message which would cause a message + violating constraints to be generated. This will be robust, + but may prevent useful communication. + + 3. Truncate fields to the upper bounds specified in X.400. + + This will prevent problems with UAs which enforce upper + bounds, but will sometimes discard useful information. + + + + +Hardcastle-Kille [Page 60] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + If the Free Form name is truncated, it may lead to breaking + RFC 822 comments, which will cause an awkward reverse + mapping. + + These options have different advantages and disadvantages, and the + choice will depend on the exact application of the gateway. + + The rest of this section concerns IPMS.IPM.heading (IPMS.Heading). + The only mandatory component of IPMS.Heading is the + IPMS.Heading.this-IPM (IPMS.IPMIdentifier). A default is generated + by the gateway. With the exception of "Received:", the values of + multiple fields are merged (e.g., If there are two "To:" fields, then + the mailboxes of both are merged to generate a single list which is + used in the IPMS.Heading.primary-recipients. Information shall be + generated from the standard RFC 822 Headers as follows: + + Date: + Ignore (Handled at MTS level) + + Received: + Ignore (Handled at MTA level) + + Message-Id: + Mapped to IPMS.Heading.this-IPM. For these, and all other + fields containing 822.msg-id the mappings of Chapter 4 are + used for each 822.msg-id. + + From: + If Sender: is present, this is mapped to + IPMS.Heading.authorizing-users. If not, it is mapped to + IPMS.Heading.originator. For this, and other components + containing addresses, the mappings of Chapter 4 are used for + each address. + + Sender: + Mapped to IPMS.Heading.originator. + + Reply-To: + Mapped to IPMS.Heading.reply-recipients. + + To: Mapped to IPMS.Heading.primary-recipients + + Cc: Mapped to IPMS.Heading.copy-recipients. + + Bcc: Mapped to IPMS.Heading.blind-copy-recipients if there is at + least one BCC: recipient. If there are no recipients in + this field, it should be mapped to a zero length sequence. + + + + +Hardcastle-Kille [Page 61] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + In-Reply-To: + If there is one value, it is mapped to + IPMS.Heading.replied-to-IPM, using the 822.phrase or + 822.msg-id mapping as appropriate. If there are several + values, they are mapped to IPMS.Heading.related-IPMs, along + with any values from a "References:" field. + + References: + Mapped to IPMS.Heading.related-IPMs. + + Keywords: + Mapped onto a heading extension. + + Subject: + Mapped to IPMS.Heading.subject. The field-body uses the + human oriented mapping referenced in Chapter 3 from ASCII to + T.61. + + Comments: + Generate an IPMS.BodyPart of type IPMS.IA5TextBodyPart with + IPMS.IA5TextBodyPart.parameters.repertoire set to the + default (ia5), containing the value of the fields, preceded + by the string "Comments: ". This body part shall precede + the other one. + + Encrypted: + Mapped onto a heading extension. + + Resent-* + Mapped onto a heading extension. + + Note that it would be possible to use a ForwardedIPMessage + for these fields, but the semantics are (arguably) slightly + different, and it is probably not worth the effort. + + Other Fields + + In particular X-* fields, and "illegal" fields in common + usage (e.g., "Fruit-of-the-day:") are mapped onto a heading + extension, unless covered by another section or appendix of + this specification. The same treatment is applied to RFC + 822 fields where the content of the field does not conform + to RFC 822 (e.g., a Date: field with unparseable syntax). + +5.1.4. Mappings to the MTS Abstract Service + + The MTS.MessageSubmissionEnvelope comprises + MTS.PerMessageSubmissionFields, and + + + +Hardcastle-Kille [Page 62] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + MTS.PerRecipientMessageSubmissionFields. The mandatory parameters + are defaulted as follows. + + MTS.PerMessageSubmissionFields.originator-name + This is always generated from 822-MTS, as defined in + Chapter 4. + + MTS.PerMessageSubmissionFields.content-type + Set to the value implied by the encoding of the IPM (2 or + 22). + + MTS.PerRecipientMessageSubmissionFields.recipient-name + These will always be supplied from 822-MTS, as defined in + Chapter 4. + + Optional components are omitted, and default components defaulted. + This means that disclosure of recipients is prohibited and conversion + is allowed. There are two exceptions to the defaulting. For + MTS.PerMessageSubmissionFields.per-message-indicators, the following + settings are made: + + - Alternate recipient is allowed, as it seems desirable to + maximise the opportunity for (reliable) delivery. + + - Content return request is set according to the issues + discussed in Section 5.2. + + MTS.PerMessageSubmissionFields.original-encoded-information-types is + a set of one element BuiltInEncodedInformationTypes.ia5-text. + + The MTS.PerMessageSubmissionFields.content-correlator is encoded as + IA5String, and contains the Subject:, Message-ID:, Date:, and + + To: fields (if present). This includes the strings "Subject:", + "Date:", "To:", "Message-ID:", and appropriate folding. This shall + be truncated to MTS.ub-content-correlator-length (512) characters. + In addition, if there is a "Subject:" field, the + MTS.PerMessageSubmissionFields.content-identifier, is set to a + printable string representation of the contents of it. If the + length of this string is greater than MTS.ub-content-id-length (16), + it should be truncated to 13 characters and the string "..." + appended. Both are used, due to the much larger upper bound of the + content correlator, and that the content id is available in + X.400(1984). + +5.1.5. Mappings to the MTA Abstract Service + + There is a need to map directly onto some aspects of the MTA Abstract + + + +Hardcastle-Kille [Page 63] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + service, for the following reasons: + + - So the the MTS Message Identifier can be generated from the + RFC 822 Message-ID:. + + - So that the submission date can be generated from the + 822.Date. + + - To prevent loss of trace information + + - To prevent RFC 822/X.400 looping caused by distribution + lists or redirects + + The following mappings are defined. + + Message-Id: + If this is present, the + MTA.PerMessageTransferFields.message-identifier is generated + from it, using the mappings described in Chapter 4. + + Date: + This is used to set the first component of + MTA.PerMessageTransferFields.trace-information + (MTA.TraceInformationElement). The 822-MTS originator is + mapped into an MTS.ORAddress, and used to derive + MTA.TraceInformationElement.global-domain-identifier. The + optional components of + MTA.TraceInformationElement.domain-supplied-information are + omitted, and the mandatory components are set as follows: + + MTA.DomainSuppliedInformation.arrival-time + This is set to the date derived from Date: + + MTA.DomainSuppliedInformation.routing-action + Set to relayed. + + The first element of + MTA.PerMessageTransferFields.internal-trace-information is + generated in an analogous manner, although this can be + dropped later in certain circumstances (see the procedures + for "Received:"). The + MTA.InternalTraceInformationElement.mta-name is derived from + the 822.domain in the 822 MTS Originator address. + + Received: + All RFC 822 trace is used to derive + MTA.PerMessageTransferFields.trace-information and + MTA.PerMessageTransferFields.internal-trace-information. + + + +Hardcastle-Kille [Page 64] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + Processing of Received: lines follows processing of Date:, + and is be done from the the bottom to the top of the RFC 822 + header (i.e., in chronological order). When other trace + elements are processed (X400-Received: in all cases and Via: + if Appendix B is supported), the relative ordering shall be + retained correctly. The initial element of + MTA.PerMessageTransferFields.trace-information will be + generated already (from Date:), unless the message has + previously been in X.400, when it will be derived from the + X.400 trace information. + + Consider the Received: field in question. If the "by" part + of the received is present, use it to derive an + MTS.GlobalDomainIdentifier. If this is different from the + one in the last element of + MTA.PerMessageTransferFields.trace-information + (MTA.TraceInformationElement.global-domain-identifier) + create a new MTA.TraceInformationElement, and optionally + remove + MTA.PerMessageTransferFields.internal-trace-information. + This removal shall be done in cases where the message is + being transferred to another MD where there is no bilateral + agreement to preserve internal trace beyond the local MD. + The trace creation is as for internal trace described below, + except that no MTA field is needed. + + Then add a new element (MTA.InternalTraceInformationElement) + to MTA.PerMessageTransferFields.internal-trace-information, + creating this if needed. This shall be done, even if + inter-MD trace is created. The + MTA.InternalTraceInformationElement.global-domain-identifier + is set to the value derived. The + MTA.InternalTraceInformationElement.mta-supplied-information + (MTA.MTASuppliedInformation) is set as follows: + + MTA.MTASuppliedInformation.arrival-time + Derived from the date of the Received: line + + MTA.MTASuppliedInformation.routing-action + Set to relayed + + The MTA.InternalTraceInformationElement.mta-name is taken + from the "by" component of the "Received:" field, truncated + to MTS.ub-mta-name-length (32). For example: + + Received: from computer-science.nottingham.ac.uk by + vs6.Cs.Ucl.AC.UK via Janet with NIFTP id aa03794; + 28 Mar 89 16:38 GMT + + + +Hardcastle-Kille [Page 65] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + Generates the string + + vs6.Cs.Ucl.AC.UK + + Note that before transferring the message to some ADMDs, additional + trace stripping may be required, as the implied path through multiple + MDs would violate ADMD policy. This will depend on bilateral + agreement with the ADMD. + +5.1.6. Mapping New Fields + + This specification defines a number of new fields for Reports, + Notifications and IP Messages in Section 5.3. As this specification + only aims to preserve existing services, a gateway conforming to this + specification does not need to map all of these fields to X.400. + + Two extended fields must be mapped, in order to prevent looping. + "DL-Expansion-History:" is mapped to + + MTA.PerMessageTransferFields.extensions.dl-expansion-history X400- + Received: must be mapped to MTA.PerMessageTransferFields.trace- + information and MTA.PerMessageTransferFields.internal-trace- + information. In cases where X400-Received: is present, the usual + mapping of Date: to generate the first element of trace should not be + done. This is because the message has come from X.400, and so the + first element of trace can be taken from the first X400-Received:. + + Some field that shall not be mapped, and should be discarded. The + following cannot be mapped back: + + - Discarded-X400-MTS-Extensions: + + - Message-Type: + + - Discarded-X400-IPMS-Extensions: + + If Message-Type: is set to "Multiple Part", then the messge is + encoded according to RFC 934, and this may be mapped on to the + corresponding X.400 structures. + + The following may cause problems, due to other information not being + mapped back (e.g., extension numbers), or due to changes made on the + RFC 822 side due to list expansion: + + - X400-Content-Type: + + - X400-Originator: + + + + +Hardcastle-Kille [Page 66] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + - X400-Recipients: + + - X400-MTS-Identifier: + + Other fields may be either discarded or mapped to X.400. It is + usually desirable and beneficial to do map, particularly to + facilitate support of a message traversing multiple gateways. These + mappings may be onto MTA, MTS, or IPMS services. The level of + support for this reverse mapping should be indicated in the gateway + conformace statement. + +5.2. Return of Contents + + It is not clear how widely supported the X.400 return of contents + service will be. Experience with X.400(1984) suggests that support + of this service may not be universal. As this service is expected in + the RFC 822 world, two approaches are specified. The choice will + depend on the use of X.400 return of contents withing the X.400 + community being serviced by the gateway. + + In environments where return of contents is widely supported, content + return can be requested as a service. The content return service can + then be passed back to the end (RFC 822) user in a straightforward + manner. + + In environments where return of contents is not widely supported, a + gateway must make special provision to handle return of contents. + For every message passing from RFC 822 -> X.400, content return + request will not be requested, and report request always will be. + When the delivery report comes back, the gateway can note that the + message has been delivered to the recipient(s) in question. If a + non-delivery report is received, a meaningful report (containing some + or all of the original message) can be sent to the 822-MTS + originator. If no report is received for a recipient, a (timeout) + failure notice shall be sent to the 822-MTS originator. The gateway + may retransmit the X.400 message if it wishes. When this approach is + taken, routing must be set up so that error reports are returned + through the same MTA. This approach may be difficult to use in + conjunction with some routing strategies. + +5.3. X.400 -> RFC 822 + +5.3.1. Basic Approach + + A single RFC 822 message is generated from the incoming IP Message, + Report, or IP Notification. All IPMS.BodyParts are mapped onto a + single RFC 822 body. Other services are mapped onto RFC 822 header + fields. Where there is no appropriate existing field, new fields are + + + +Hardcastle-Kille [Page 67] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + defined for IPMS, MTS and MTA services. + + The gateway mechanisms will correspond to MTS Delivery. As with + submission, there are aspects where the MTA (transfer) services are + also used. In particular, there is an optimisation to allow for + multiple 822-MTS recipients. + +5.3.2. RFC 822 Settings + + An RFC 822 Service requires to have a number of mandatory fields in + the RFC 822 Header. Some 822-MTS services mandate specification of + an 822-MTS Originator. Even in cases where this is optional, it is + usually desirable to specify a value. The following defaults are + defined, which shall be used if the mappings specified do not derive + a value: + + 822-MTS Originator + If this is not generated by the mapping (e.g., for a + Delivery Report), a value pointing at a gateway + administrator shall be assigned. + + Date: + A value will always be generated + + From:If this is not generated by the mapping, it is assigned + equal to the 822-MTS Originator. If this is gateway + generated, an appropriate 822.phrase shall be added. + + At least one recipient field + If no recipient fields are generated, a field "To: list:;", + shall be added. + + This will ensure minimal RFC 822 compliance. When generating RFC 822 + headers, folding may be used. It is recommended to do this, + following the guidelines of RFC 822. + +5.3.3. Basic Mappings + +5.3.3.1. Encoded Information Types + + This mapping from MTS.EncodedInformationTypes is needed in several + disconnected places. EBNF is defined as follows: + + encoded-info = 1#encoded-type + + encoded-type = built-in-eit / object-identifier + + built-in-eit = "Undefined" ; undefined (0) + + + +Hardcastle-Kille [Page 68] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + / "Telex" ; tLX (1) + / "IA5-Text" ; iA5Text (2) + / "G3-Fax" ; g3Fax (3) + / "TIF0" ; tIF0 (4) + / "Teletex" ; tTX (5) + / "Videotex" ; videotex (6) + / "Voice" ; voice (7) + / "SFD" ; sFD (8) + / "TIF1" ; tIF1 (9) + + MTS.EncodedInformationTypes is mapped onto EBNF.encoded-info. + MTS.EncodedInformationTypes.non-basic-parameters is ignored. Built + in types are mapped onto fixed strings (compatible with X.400(1984) + and RFC 987), and other types are mapped onto EBNF.object-identifier. + +5.3.3.2. Global Domain Identifier + + The following simple EBNF is used to represent + MTS.GlobalDomainIdentifier: + + global-id = std-or-address + + This is encoded using the std-or-address syntax, for the attributes + within the Global Domain Identifier. + +5.3.4. Mappings from the IP Message + + Consider that an IPM has to be mapped to RFC 822. The IPMS.IPM + comprises an IPMS.IPM.heading and IPMS.IPM.body. The heading is + considered first. Some EBNF for new fields is defined: + + ipms-field = "Obsoletes" ":" 1#msg-id + / "Expiry-Date" ":" date-time + / "Reply-By" ":" date-time + / "Importance" ":" importance + / "Sensitivity" ":" sensitivity + / "Autoforwarded" ":" boolean + / "Incomplete-Copy" ":" + / "Language" ":" language + / "Message-Type" ":" message-type + / "Discarded-X400-IPMS-Extensions" ":" 1#oid + + + + importance = "low" / "normal" / "high" + + + sensitivity = "Personal" / "Private" / + + + +Hardcastle-Kille [Page 69] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + "Company-Confidential" + + language = 2*ALPHA [ language-description ] + language-description = printable-string + + + + message-type = "Delivery Report" + / "InterPersonal Notification" + / "Multiple Part" + + The mappings and actions for the IPMS.Heading is now specified for + each element. Addresses, and Message Identifiers are mapped + according to Chapter 4. Other mappings are explained, or are + straightforward (algorithmic). If a field with addresses contains + zero elements, it should be discarded, execpt for + IPMS.Heading.blind-copy-recipients, which can be mapped onto BCC: + (the only RFC 822 field which allows zero recipients). + + IPMS.Heading.this-IPM + Mapped to "Message-ID:". + + IPMS.Heading.originator + If IPMS.Heading.authorizing-users is present this is mapped + to Sender:, if not to "From:". + + IPMS.Heading.authorizing-users + Mapped to "From:". + + IPMS.Heading.primary-recipients + Mapped to "To:". + + IPMS.Heading.copy-recipients + Mapped to "Cc:". + + IPMS.Heading.blind-copy-recipients + Mapped to "Bcc:". + + IPMS.Heading.replied-to-ipm + Mapped to "In-Reply-To:". + + IPMS.Heading.obsoleted-IPMs + Mapped to the extended RFC 822 field "Obsoletes:" + + IPMS.Heading.related-IPMs + Mapped to "References:". + + + + + +Hardcastle-Kille [Page 70] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + IPMS.Heading.subject + Mapped to "Subject:". The contents are converted to ASCII + (as defined in Chapter 3). Any CRLF are not mapped, but are + used as points at which the subject field must be folded. + + IPMS.Heading.expiry-time + Mapped to the extended RFC 822 field "Expiry-Date:". + + IPMS.Heading.reply-time + Mapped to the extended RFC 822 field "Reply-By:". + + IPMS.Heading.reply-recipients + Mapped to "Reply-To:". + + IPMS.Heading.importance + Mapped to the extended RFC 822 field "Importance:". + + IPMS.Heading.sensitivity + Mapped to the extended RFC 822 field "Sensitivity:". + + IPMS.Heading.autoforwarded + Mapped to the extended RFC 822 field "Autoforwarded:". + + The standard extensions (Annex H of X.420 / ISO 10021-7) are + mapped as follows: + + incomplete-copy + Mapped to the extended RFC 822 field "Incomplete-Copy:". + + language + Mapped to the extended RFC 822 field "Language:", filling in + the two letter code. The language-description may filled in + with a human readable description of the language, and it is + recommended to do this. + + If the RFC 822 extended header is found, this shall be mapped onto an + RFC 822 header, as described in Section 5.1.2. + + If a non-standard extension is found, it shall be discarded, unless + the gateway understands the extension and can perform an appropriate + mapping onto an RFC 822 header field. If extensions are discarded, + the list is indicated in the extended RFC 822 field "Discarded-X400- + IPMS-Extensions:". + + The IPMS.Body is mapped into the RFC 822 message body. Each + IPMS.BodyPart is converted to ASCII as follows: + + + + + +Hardcastle-Kille [Page 71] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + IPMS.IA5Text + The mapping is straightforward (see Chapter 3). + + IPMS.MessageBodyPart + The X.400 -> RFC 822 mapping is recursively applied, to + generate an RFC 822 Message. If present, the + IPMS.MessageBodyPart.parameters.delivery-envelope is used + for the MTS Abstract Service Mappings. If present, the + IPMS.MessageBodyPart.parameters.delivery-time is mapped to + the extended RFC 822 field "Delivery-Date:". + + Other + If other body parts can be mapped to IA5, either by use of + mappings defined in X.408 [CCITT88a], or by other reasonable + mappings, this shall be done unless content conversion is + prohibited. + + If some or all of the body parts cannot be converted there are three + options. All of these conform to this standard. A different choice + may be made for the case where no body part can be converted: + + 1. The first option is to reject the message, and send a non- + delivery notification. This must always be done if + conversion is prohibited. + + 2. The second option is to map a missing body part to something + of the style: + + ********************************* + + There was a foobarhere + + The widget gateway ate it + + ********************************* + + This will allow some useful information to be transferred. + As the recipient is likely to be a human (IPMS), then + suitable action will usually be possible. + + 3. Finally both may be done. In this case, the supplementary + information in the (positive) Delivery Report shall make + clear that something was sent on to the recipient with + substantial loss of information. + + Where there is more than one IPMS.BodyPart, the mapping defined by + Rose and Stefferud in [Rose85a], is used to map the separate + IPMS.BodyParts in the single RFC 822 message body. If this is done, + + + +Hardcastle-Kille [Page 72] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + a "Message-Type:" field with value "Multiple part" shall be added, + which will indicate to a receiving gateway that the message may be + unfolded according to RFC 934. + + Note:There is currently work ongoing to produce an upgrade to RFC + 934, which also allows for support of body parts with non- + ASCII content (MIME). When this work is released as an RFC, + this specification will be updated to refer to it instead + for RFC 934. + + For backwards compatibility with RFC 987, the following procedures + shall also be followed. If there are two IA5 body parts, and the + first starts with the string "RFC-822-Headers:" as the first line, + then the remainder of this body part shall be appended to the RFC 822 + header. + + An example message, illustrating a number of aspects is given below. + +Return-Path:<@mhs-relay.ac.uk:stephen.harrison@gosip-uk.hmg.gold-400.gb> +Received: from mhs-relay.ac.uk by bells.cs.ucl.ac.uk via JANET + with NIFTP id <7906-0@bells.cs.ucl.ac.uk>; + Thu, 30 May 1991 18:24:55 +0100 +X400-Received: by mta "mhs-relay.ac.uk" in + /PRMD=uk.ac/ADMD= /C=gb/; Relayed; + Thu, 30 May 1991 18:23:26 +0100 +X400-Received: by /PRMD=HMG/ADMD=GOLD 400/C=GB/; Relayed; + Thu, 30 May 1991 18:20:27 +0100 +Message-Type: Multiple Part +Date: Thu, 30 May 1991 18:20:27 +0100 +X400-Originator: Stephen.Harrison@gosip-uk.hmg.gold-400.gb +X400-MTS-Identifier: + [/PRMD=HMG/ADMD=GOLD 400/C=GB/;PC1000-910530172027-57D8] +Original-Encoded-Information-Types: ia5, undefined +X400-Content-Type: P2-1984 (2) +Content-Identifier: Email Problems +From: Stephen.Harrison@gosip-uk.hmg.gold-400.gb (Tel +44 71 217 3487) +Message-ID: <PC1000-910530172027-57D8*@MHS> +To: Jim Craigie <NTIN36@gec-b.rutherford.ac.uk> + (Receipt Notification Requested) (Non Receipt Notification Requested), + Tony Bates <tony@ean-relay.ac.uk> (Receipt Notification Requested), + Steve Kille <S.Kille@cs.ucl.ac.uk> (Receipt Notification Requested) +Subject: Email Problems +Sender: Stephen.Harrison@gosip-uk.hmg.gold-400.gb + + +------------------------------ Start of body part 1 + +Hope you gentlemen....... + + + +Hardcastle-Kille [Page 73] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + +Regards, + +Stephen Harrison +UK GOSIP Project + +------------------------------ Start of forwarded message 1 + +From: Urs Eppenberger <Eppenberger@verw.switch.ch> +Message-ID: + <562*/S=Eppenberger/OU=verw/O=switch/PRMD=SWITCH/ADMD=ARCOM/C=CH/@MHS> +To: "Stephen.Harrison" <Stephen.Harrison@gosip-uk.hmg.gold-400.gb> +Cc: kimura@bsdarc.bsd.fc.nec.co.jp +Subject: Response to Email link + + +- ------------------------------ Start of body part 1 + +Dear Mr Harrison...... + + +- ------------------------------ End of body part 1 + +------------------------------ End of forwarded message 1 + +5.3.5. Mappings from an IP Notification + + A message is generated, with the following fields: + + From: + Set to the IPMS.IPN.ipn-originator. + + To: Set to the recipient from MTS.MessageSubmissionEnvelope. + If there have been redirects, the original address should be + used. + + Subject: + Set to the string "X.400 Inter-Personal Notification" for a + receipt notification and to "X.400 Inter-Personal + Notification (failure)" for a non-receipt notification. + + Message-Type: + Set to "InterPersonal Notification" + + References: + Set to IPMS.IPN.subject-ipm + + The following EBNF is defined for the body of the Message. This + format is defined to ensure that all information from an + + + +Hardcastle-Kille [Page 74] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + interpersonal notification is available to the end user in a uniform + manner. + + ipn-body-format = ipn-description <CRLF> + [ ipn-extra-information <CRLF> ] + [ ipn-content-return ] + + ipn-description = ipn-receipt / ipn-non-receipt + + ipn-receipt = "Your message to:" preferred-recipient <CRLF> + "was received at" receipt-time <CRLF> <CRLF> + "This notification was generated" + acknowledgement-mode <CRLF> + "The following extra information was given:" <CRLF> + ipn-suppl <CRLF> + + ipn-non-receipt "Your message to:" + preferred-recipient <CRLF> + ipn-reason + + + ipn-reason = ipn-discarded / ipn-auto-forwarded + + ipn-discarded = "was discarded for the following reason:" + discard-reason <CRLF> + + ipn-auto-forwarded = "was automatically forwarded." <CRLF> + [ "The following comment was made:" + auto-comment ] + + + ipn-extra-information = + "The following information types were converted:" + encoded-info + + ipn-content-return = "The Original Message is not available" + / "The Original Message follows:" + <CRLF> <CRLF> message + + preferred-recipient = mailbox + receipt-time = date-time + auto-comment = printablestring + ipn-suppl = printablestring + + + discard-reason = "Expired" / "Obsoleted" / + "User Subscription Terminated" + + + + +Hardcastle-Kille [Page 75] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + acknowledgement-mode = "Manually" / "Automatically" + + The mappings for elements of the common fields of IPMS.IPN + (IPMS.CommonFields) onto this structure and the message header are: + + subject-ipm + Mapped to "References:" + + ipn-originator + Mapped to "From:". + + ipn-preferred-recipient + Mapped to EBNF.preferred-recipient + + conversion-eits + Mapped to EBNF.encoded-info in EBNF.ipn-extra-information + + The mappings for elements of IPMS.IPN.non-receipt-fields + (IPMS.NonReceiptFields) are: + + non-receipt-reason + Used to select between EBNF.ipn-discarded and + EBNF.ipn-auto-forwarded + + discard-reason + Mapped to EBNF.discard-reason + + auto-forward-comment + Mapped to EBNF.auto-comment + + returned-ipm + This applies only to non-receipt notifications. + EBNF.ipn-content-return should always be omitted for receipt + notifications, and always be present in non-receipt + notifications. If present, the second option of + EBNF.ipn-content-return is chosen, and an RFC 822 mapping of + the message included. Otherwise the first option is chosen. + + The mappings for elements of IPMS.IPN.receipt-fields + (IPMS.ReceiptFields) are: + + receipt-time + Mapped to EBNF.receipt-time + + acknowledgement-mode + Mapped to EBNF.acknowledgement-mode + + + + + +Hardcastle-Kille [Page 76] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + suppl-receipt-info + Mapped to EBNF.ipn-suppl + + An example notification is: + + From: Steve Kille <steve@cs.ucl.ac.uk> + To: Julian Onions <jpo@computer-science.nottingham.ac.uk> + Subject: X.400 Inter-personal Notification + Message-Type: InterPersonal Notification + References: <1229.614418325@UK.AC.NOTT.CS> + Date: Wed, 21 Jun 89 08:45:25 +0100 + + Your message to: Steve Kille <steve@cs.ucl.ac.uk> + was automatically forwarded. + The following comment was made: + Sent on to a random destination + + The following information types were converted: g3fax + +5.3.6. Mappings from the MTS Abstract Service + + This section describes the MTS mappings for User Messages (IPM and + IPN). This mapping is defined by specifying the mapping of + MTS.MessageDeliveryEnvelope. The following extensions to RFC 822 are + defined to support this mapping: + + mts-field = "X400-MTS-Identifier" ":" mts-msg-id + / "X400-Originator" ":" mailbox + / "X400-Recipients" ":" 1#mailbox + / "Original-Encoded-Information-Types" ":" + encoded-info + / "X400-Content-Type" ":" mts-content-type + / "Content-Identifier" ":" printablestring + / "Priority" ":" priority + / "Originator-Return-Address" ":" 1#mailbox + / "DL-Expansion-History" ":" mailbox ";" date-time ";" + / "Conversion" ":" prohibition + / "Conversion-With-Loss" ":" prohibition + / "Requested-Delivery-Method" ":" + 1*( labelled-integer ) + / "Delivery-Date" ":" date-time + / "Discarded-X400-MTS-Extensions" ":" + 1#( oid / labelled-integer ) + + + prohibition = "Prohibited" / "Allowed" + + mts-msg-id = "[" global-id ";" *text "]" + + + +Hardcastle-Kille [Page 77] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + mts-content-type = "P2" / labelled-integer + / object-identifer + + priority = "normal" / "non-urgent" / "urgent" + + The mappings for each element of MTS.MessageDeliveryEnvelope can now + be considered. + + MTS.MessageDeliveryEnvelope.message-delivery-identifier + Mapped to the extended RFC 822 field "X400-MTS-Identifier:". + + MTS.MessageDeliveryEnvelope.message-delivery-time + Discarded, as this time will be represented in an + appropriate trace element. + + The mappings for elements of + MTS.MessageDeliveryEnvelope.other-fields + (MTS.OtherMessageDeliveryFields) are: + + content-type + Mapped to the extended RFC 822 field "X400-Content-Type:". + The string "P2" is retained for backwards compatibility with + RFC 987. This shall not be generated, and either the + EBNF.labelled-integer or EBNF.object-identifier encoding + used. + + originator-name + Mapped to the 822-MTS originator, and to the extended RFC + 822 field "X400-Originator:". This is described in + Section 4.6.2. + + original-encoded-information-types + Mapped to the extended RFC 822 field + "Original-Encoded-Information-Types:". + + priority + Mapped to the extended RFC 822 field "Priority:". + + delivery-flags + If the conversion-prohibited bit is set, add an extended RFC + 822 field "Conversion:". + + this-recipient-name and other-recipient-names + + originally-intended-recipient-name + The handling of these elements is described in + Section 4.6.2. + + + + +Hardcastle-Kille [Page 78] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + converted-encoded-information-types + Discarded, as it will always be IA5 only. + + message-submission-time + Mapped to Date:. + + content-identifier + Mapped to the extended RFC 822 field "Content-Identifier:". + + If any extensions (MTS.MessageDeliveryEnvelope.other- + fields.extensions) are present, and they are marked as critical for + transfer or delivery, then the message shall be rejected. The + extensions (MTS.MessageDeliveryEnvelope.other-fields.extensions) are + mapped as follows. + + conversion-with-loss-prohibited + If set to + MTS.ConversionWithLossProhibited.conversion-with-loss-prohibited, + then add the extended RFC 822 field "Conversion-With-Loss:". + + requested-delivery-method + Mapped to the extended RFC 822 field + "Requested-Delivery-Method:". + + originator-return-address + Mapped to the extended RFC 822 field + "Originator-Return-Address:". + + physical-forwarding-address-request + physical-delivery-modes + registered-mail-type + recipient-number-for-advice + physical-rendition-attributes + physical-delivery-report-request + physical-forwarding-prohibited + + + These elements are only appropriate for physical delivery. + They are represented as comments in the "X400-Recipients:" + field, as described in Section 4.6.2.2. + + originator-certificate + message-token + content-confidentiality-algorithm-identifier + content-integrity-check + message-origin-authentication-check + message-security-label + proof-of-delivery-request + + + +Hardcastle-Kille [Page 79] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + These elements imply use of security services not available + in the RFC 822 environment. If they are marked as critical + for transfer or delivery, then the message shall be + rejected. Otherwise they are discarded. + + redirection-history + This is described in Section 4.6.2. + + dl-expansion-history + Each element is mapped to the extended RFC 822 field + "DL-Expansion-History:". They shall be ordered in the + message header, so that the most recent expansion comes + first (same order as trace). + + If any MTS (or MTA) Extensions not specified in X.400 are present, + and they are marked as critical for transfer or delivery, then the + message shall be rejected. If they are not so marked, they can + safely be discarded. The list of discarded fields shall be indicated + in the extended header "Discarded-X400-MTS-Extensions:". + +5.3.7. Mappings from the MTA Abstract Service + + There are some mappings at the MTA Abstract Service level which are + done for IPM and IPN. These can be derived from + MTA.MessageTransferEnvelope. The reasons for the mappings at this + level, and the violation of layering are: + + - Allowing for multiple recipients to share a single RFC 822 + message + + - Making the X.400 trace information available on the RFC 822 + side + + - Making any information on deferred delivery available + + The 822-MTS recipients are calculated from the full list of X.400 + recipients. This is all of the members of + MTA.MessageTransferEnvelope.per-recipient-fields being passed through + the gateway, where the responsibility bit is set. In some cases, a + different RFC 822 message would be calculated for each recipient, due + to differing service requests for each recipient. As discussed in + 4.6.2..2, this specification allows either for multiple messages to + be generated, or for the per- recipient information to be discarded. + + The following EBNF is defined for extended RFC 822 headers: + + mta-field = "X400-Received" ":" x400-trace + / "Deferred-Delivery" ":" date-time + + + +Hardcastle-Kille [Page 80] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + / "Latest-Delivery-Time" ":" date-time + + x400-trace = "by" md-and-mta ";" + [ "deferred until" date-time ";" ] + [ "converted" "(" encoded-info ")" ";" ] + [ "attempted" md-or-mta ";" ] + action-list + ";" arrival-time + + + md-and-mta = [ "mta" mta "in" ] global-id + mta = word + arrival-time = date-time + + md-or-mta = "MD" global-id + / "MTA" mta + + Action-list = 1#action + action = "Redirected" + / "Expanded" + / "Relayed" + / "Rerouted" + + Note the EBNF.mta is encoded as 822.word. If the character set does + no allow encoding as 822.atom, the 822.quoted-string encoding is + used. + + If MTA.PerMessageTransferFields.deferred-delivery-time is present, it + is used to generate a Deferred-Delivery: field. For some reason, + X.400 does not make this information available at the MTS level on + delivery. X.400 profiles, and in particular the CEN/CENELEC profile + for X.400(1984) [Systems85a], specify that this element must be + supported at the first MTA. If it is not, the function may + optionally be implemented by the gateway: that is, the gateway may + hold the message until the time specified in the protocol element. + Thus, the value of this element will usually be in the past. For + this reason, the extended RFC 822 field is primarily for information. + + Merge MTA.PerMessageTransferFields.trace-information, and + MTA.PerMessageTransferFields.internal-trace-information to produce a + single ordered trace list. If Internal trace from other management + domains has not been stripped, this may require complex interleaving. + Where an element of internal trace and external trace are identical, + except for the MTA in the internal trace, only the internal trace + element shall be presented. Use this to generate a sequence of + "X400-Received:" fields. The only difference between external trace + and internal trace will be the extra MTA information in internal + trace elements. + + + +Hardcastle-Kille [Page 81] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + When generating an RFC 822 message all trace fields (X400-Received + and Received) shall be at the beginning of the header, before any + other fields. Trace shall be in chronological order, with the most + recent element at the front of the message. This ordering is + determined from the order of the fields, not from timestamps in the + trace, as there is no guarantee of clock synchronisation. A simple + example trace (external) is: + + X400-Received: by /PRMD=UK.AC/ADMD=Gold 400/C=GB/ ; Relayed ; + Tue, 20 Jun 89 19:25:11 +0100 + + A more complex example (internal): + + X400-Received: by mta "UK.AC.UCL.CS" + in /PRMD=UK.AC/ADMD=Gold 400/C=GB/ ; + deferred until Tue, 20 Jun 89 14:24:22 +0100 ; + converted (undefined, g3fax) ";" attempted /ADMD=Foo/C=GB/ ; + Relayed, Expanded, Redirected ; Tue, 20 Jun 89 19:25:11 +0100 + +5.3.8. Mappings from Report Delivery + + Delivery reports are mapped at the MTS service level. This means + that only reports destined for the MTS user will be mapped. Some + additional services are also taken from the MTA service. + +5.3.8.1. MTS Mappings + + A Delivery Report service will be represented as + MTS.ReportDeliveryEnvelope, which comprises of per-report-fields + (MTS.PerReportDeliveryFields) and per-recipient-fields. + + A message is generated with the following fields: + + From: + An administrator at the gateway system. This is also the + 822-MTS originator. + + To: A mapping of the + MTA.ReportTransferEnvelope.report-destination-name. This is + also the 822-MTS recipient. + + Message-Type: + Set to "Delivery Report". + + Subject: + The EBNF for the subject line is: + + + + + +Hardcastle-Kille [Page 82] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + subject-line = "Delivery-Report" "(" status ")" + [ "for" destination ] + + status = "success" / "failure" / "success and failures" + + destination = mailbox / "MTA" word + + The format of the body of the message is defined to ensure that all + information is conveyed to the RFC 822 user in a consistent manner. + The format is structured as if it was a message coming from X.400, + with the description in one body part, and a forwarded message + (return of content) in the second. This structure is useful to the + RFC 822 recipient, as it enables the original message to be + extracted. The first body part is structured as follows: + +1. A few lines giving keywords to indicate the original + message. + +2. A human summary of the status of each recipient being + reported on. + +3. A clearly marked section which contains detailed information + extracted from the report. This is marked clearly, as it + will not be comprehensible to the average user. It is + retained, as it may be critical to diagnosing an obscure + problem. + + This section may be omitted in positive DRs, and it is + recommended that this is appropriate for most gateways. + + dr-body-format = dr-summary <CRLF> + dr-recipients <CRLF> + dr-administrator-info-envelope <CRLF> + dr-content-return + + + dr-content-return = "The Original Message is not available" + / "The Original Message follows:" + + dr-summary = "This report relates to your message:" <CRLF> + content-correlator <CRLF> <CRLF> + "of" date-time <CRLF> <CRLF> + + + dr-recipients = *(dr-recipient <CRLF> <CRLF>) + + dr-recipient = dr-recip-success / dr-recip-failure + + + + +Hardcastle-Kille [Page 83] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + dr-recip-success = + "Your message was successfully delivered to:" + mailbox "at" date-time + + + dr-recip-failure = "Your message was not delivered to:" + mailbox <CRLF> + "for the following reason:" *word + + + dr-administrator-info-envelope = 3*( "*" text <CRLF> ) + + + dr-administrator-info = + "**** The following information is directed towards" + "the local administrator" <CRLF> + "**** and is not intended for the end user" <CRLF> <CRLF> + "DR generated by:" report-point <CRLF> + "at" date-time <CRLF> <CRLF> + "Converted to RFC 822 at" mta <CRLF> + "at" date-time <CRLF> <CRLF> + "Delivery Report Contents:" <CRLF> <CRLF> + drc-field-list <CRLF> + "***** End of administration information" + + drc-field-list = *(drc-field <CRLF>) + + drc-field = "Subject-Submision-Identifier" ":" + mts-msg-id + / "Content-Identifier" ":" printablestring + / "Content-Type" ":" mts-content-type + / "Original-Encoded-Information-Types" ":" + encoded-info + / "Originator-and-DL-Expansion-History" ":" + dl-history + / "Reporting-DL-Name" ":" mailbox + / "Content-Correlator" ":" content-correlator + / "Recipient-Info" ":" recipient-info + / "Subject-Intermediate-Trace-Information" ":" + x400-trace + + + recipient-info = mailbox "," std-or ";" + report-type + [ "converted eits" encoded-info ";" ] + [ "originally intended recipient" + mailbox "," std-or ";" ] + [ "last trace" [ encoded-info ] date-time ";" ] + + + +Hardcastle-Kille [Page 84] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + [ "supplementary info" <"> printablestring <"> ";" ] + [ "redirection history" 1#redirection ";" + [ "physical forwarding address" + printablestring ";" ] + + + report-type = "SUCCESS" drc-success + / "FAILURE" drc-failure + + drc-success = "delivered at" date-time ";" + [ "type of MTS user" labelled-integer ";" ] + + drc-failure = "reason" labelled-integer ";" + [ "diagnostic" labelled-integer ";" ] + + + report-point = [ "mta" word "in" ] global-id + content-correlator = *word + dl-history = 1#( mailbox "(" date-time ")") + + The format is defined as a fixed definition of an the outer level + (EBNF.dr-body-format). The element EBNF.dr-administrator-info- + envelope, provides a means of encapsulating a section of the header + in a manner which is clear to the end user. Each line of this + section begins with "*". Each element of EBNF.text within %EBNF.dr- + administrator-info-envelope must not contain <CRLF>. This is used to + wrap up EBNF.dr-administrator-info, which will generate a sequenece + of lines not starting with "*". EBNF.drc-fields may be folded using + the RFC 822 folding rules. + + The elements of MTS.ReportDeliveryEnvelope.per-report-fields are + mapped as follows onto extended RFC 822 fields: + + subject-submission-identifier + Mapped to EBNF.drc-field (Subject-Submission-Identifier) + + content-identifier + Mapped to EBNF.drc-field (Content-Identifier). This should + also be used in EBNF.dr-summary if there is no Content + Correlator present. + + content-type + Mapped to EBNF.drc-field (Content-Type) + + original-encoded-information-types + Mapped to EBNF.drc-field (Encoded-Info) + + + + + +Hardcastle-Kille [Page 85] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + The extensions from MTS.ReportDeliveryEnvelope.per-report- + fields.extensions are mapped as follows: + + originator-and-DL-expansion-history + Mapped to EBNF.drc-field (Originator-and-DL-Expansion- + History) + + reporting-DL-name + Mapped to EBNF.drc-field (Reporting-DL-Name) + + content-correlator + Mapped to EBNF.content-correlator, provided that the + encoding is IA5String (this will always be the case). This + is used in EBNF.dr-summary and EBNF.drc-field-list. In the + former, LWSP may be added, in order to improve the layout of + the message. + + message-security-label reporting-MTA-certificate report-origin- + authentication-check + + These security parameters will not be present unless there + is an error in a remote MTA. If they are present, they + shall be discarded in preference to discarding the whole + report. + + For each element of MTS.ReportDeliveryEnvelope.per-recipient-fields, + a value of EBNF.dr-recipient, and an EBNF.drc-field (Recipient-Info) + is generated. The components are mapped as follows. + + actual-recipient-name + Used to generate the first EBNF.mailbox and EBNF.std-or in + EBNF.recipient-info. Both RFC 822 and X.400 forms are + given, as there may be a problem in the mapping tables. It + also generates the EBNF.mailbox in EBNF.dr-recip-success or + EBNF.dr-recip-failure. + + report + If it is MTS.Report.delivery, then set EBNF.dr-recipient to + EBNF.dr-recip-success, and similarly set EBNF.report-type, + filling in EBNF.drc-success. If it is a failure, set + EBNF.dr-recipient to EBNF.dr-recip-failure, making a human + interpretation of the reason and diagnostic codes, and + including any supplementary information. EBNF.drc-failure + is filled in systematically. + + converted-encoded-information-types + Set EBNF.drc-field ("converted eits") + + + + +Hardcastle-Kille [Page 86] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + originally-intended-recipient + Set the second ("originally intended recipient") mailbox and + std-or in EBNF.drc-field. + + supplementary-info + Set EBNF.drc-field ("supplementary info"), and include this + information in EBNF.dr-recip-failure. + + redirection-history + Set EBNF.drc-field ("redirection history") + + physical-forwarding-address + Set ENBF.drc-field ("physical forwarding address") + + recipient-certificate + Discard + + proof-of-delivery + Discard + + Any unknown extensions shall be discarded, irrespective of + criticality. + + The original message, or an extract from it, shall be included in the + delivery port if it is available. The original message will usually + be available at the gateway, as discussed in Section 5.2. If the + original message is available, but of erroneous format, a dump of the + ASN.1 may be included. This is recommended, but not required. + +5.3.8.2. MTA Mappings + + The single 822-MTS recipient is constructed from + MTA.ReportTransferEnvelope.report-destination-name, using the + mappings of Chapter 4. Unlike with a user message, this information + is not available at the MTS level. + + The following additional mappings are made: + + MTA.ReportTransferEnvelope.report-destination-name + This is used to generate the To: field. + + MTA.ReportTransferEnvelope.identifier + Mapped to the extended RFC 822 field "X400-MTS-Identifier:". + It may also be used to derive a "Message-Id:" field. + + MTA.ReportTransferEnvelope.trace-information + and + + + + +Hardcastle-Kille [Page 87] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + MTA.ReportTransferEnvelope.internal-trace-information + Mapped onto the extended RFC 822 field "X400-Received:", as + described in Section 5.3.7. The first element is also used + to generate the "Date:" field, and the EBNF.report-point. + + MTA.PerRecipientReportTransferFields.last-trace-information + Mapped to EBNF.recipient-info (last trace) + + MTA.PerReportTransferFields.subject-intermediate-trace- + information Mapped to EBNF.drc-field (Subject-Intermediate- + Trace-Information). These fields are ordered so that the + most recent trace element comes first. + +5.3.8.3. Example Delivery Reports + + Example Delivery Report 1: + + Return-Path: <postmaster@cs.ucl.ac.uk> + Received: from cs.ucl.ac.uk by bells.cs.ucl.ac.uk + via Delivery Reports Channel id <27699-0@bells.cs.ucl.ac.uk>; + Thu, 7 Feb 1991 15:48:39 +0000 + From: UCL-CS MTA <postmaster@cs.ucl.ac.uk> + To: S.Kille@cs.ucl.ac.uk + Subject: Delivery Report (failure) for H.Hildegard@bbn.com + Message-Type: Delivery Report + Date: Thu, 7 Feb 1991 15:48:39 +0000 + Message-ID: <"bells.cs.u.694:07.01.91.15.48.34"@cs.ucl.ac.uk> + Content-Identifier: Greetings. + + + ------------------------------ Start of body part 1 + + This report relates to your message: Greetings. + of Thu, 7 Feb 1991 15:48:20 +0000 + + Your message was not delivered to + H.Hildegard@bbn.com for the following reason: + Bad Address + MTA 'bbn.com' gives error message (USER) Unknown user + name in "H.Hildegard@bbn.com" + + +***** The following information is directed towards the local +***** administrator and is not intended for the end user +* +* DR generated by mta bells.cs.ucl.ac.uk +* in /PRMD=uk.ac/ADMD=gold 400/C=gb/ +* at Thu, 7 Feb 1991 15:48:34 +0000 + + + +Hardcastle-Kille [Page 88] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + +* +* Converted to RFC 822 at bells.cs.ucl.ac.uk +* at Thu, 7 Feb 1991 15:48:40 +0000 +* + ..... continued on next page + +* Delivery Report Contents: +* +* Subject-Submission-Identifier: +* [/PRMD=uk.ac/ADMD=gold 400/C=gb/;<1803.665941698@UK.AC.UCL.CS>] +* Content-Identifier: Greetings. +* Subject-Intermediate-Trace-Information: + /PRMD=uk.ac/ADMD=gold 400/C=gb/; +* arrival Thu, 7 Feb 1991 15:48:20 +0000 action Relayed + +* Subject-Intermediate-Trace-Information: + /PRMD=uk.ac/ADMD=gold 400/C=gb/; +* arrival Thu, 7 Feb 1991 15:48:18 +0000 action Relayed +* Recipient-Info: H.Hildegard@bbn.com, +* /RFC-822=H.Hildegard(a)bbn.com/OU=cs/O=ucl + /PRMD=uk.ac/ADMD=gold 400/C=gb/; +* FAILURE reason Unable-To-Transfer (1); +* diagnostic Unrecognised-ORName (0); +* last trace (ia5) Thu, 7 Feb 1991 15:48:18 +0000; +* supplementary info "MTA 'bbn.com' gives error message (USER) +* Unknown user name in "H.Hildegard@bbn.com""; +****** End of administration information + +The Original Message follows: + + +------------------------------ Start of forwarded message 1 + +Received: from glenlivet.cs.ucl.ac.uk by bells.cs.ucl.ac.uk + with SMTP inbound id <27689-0@bells.cs.ucl.ac.uk>; + Thu, 7 Feb 1991 15:48:21 +0000 +To: H.Hildegard@bbn.com +Subject: Greetings. +Phone: +44-71-380-7294 +Date: Thu, 07 Feb 91 15:48:18 +0000 +Message-ID: <1803.665941698@UK.AC.UCL.CS> +From: Steve Kille <S.Kille@cs.ucl.ac.uk> + + +Steve + +------------------------------ End of forwarded message 1 +Example Delivery Report 2: + + + +Hardcastle-Kille [Page 89] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + +Return-Path: <postmaster@cs.ucl.ac.uk> +Received: from cs.ucl.ac.uk by bells.cs.ucl.ac.uk + via Delivery Reports Channel id <27718-0@bells.cs.ucl.ac.uk>; + Thu, 7 Feb 1991 15:49:11 +0000 +X400-Received: by mta bells.cs.ucl.ac.uk in + /PRMD=uk.ac/ADMD=gold 400/C=gb/; + Relayed; Thu, 7 Feb 1991 15:49:08 +0000 +X400-Received: by /PRMD=DGC/ADMD=GOLD 400/C=GB/; Relayed; + Thu, 7 Feb 1991 15:48:40 +0000 +From: UCL-CS MTA <postmaster@cs.ucl.ac.uk> +To: S.Kille@cs.ucl.ac.uk +Subject: Delivery Report (failure) for + j.nosuchuser@dle.cambridge.DGC.gold-400.gb +Message-Type: Delivery Report +Date: Thu, 7 Feb 1991 15:49:11 +0000 +Message-ID: <"DLE/910207154840Z/000"@cs.ucl.ac.uk> +Content-Identifier: A useful mess... + +This report relates to your message: A useful mess... +Your message was not delivered to + j.nosuchuser@dle.cambridge.DGC.gold-400.gb + for the following reason: + Bad Address + DG 21187: (CEO POA) Unknown addressee. + + +***** The following information is directed towards the local +***** administrator and is not intended for the end user +* +* DR generated by /PRMD=DGC/ADMD=GOLD 400/C=GB/ +* at Thu, 7 Feb 1991 15:48:40 +0000 +* +* Converted to RFC 822 at bells.cs.ucl.ac.uk +* at Thu, 7 Feb 1991 15:49:12 +0000 +* +* Delivery Report Contents: +* +* Subject-Submission-Identifier: +* [/PRMD=uk.ac/ADMD=gold 400/C=gb/;<1796.665941626@UK.AC.UCL.CS>] +* Content-Identifier: A useful mess... +* Recipient-Info: j.nosuchuser@dle.cambridge.DGC.gold-400.gb, +* /I=j/S=nosuchuser/OU=dle/O=cambridge/PRMD=DGC/ADMD=GOLD 400/C=GB/; +* FAILURE reason Unable-To-Transfer (1); +* diagnostic Unrecognised-ORName (0); +* supplementary info "DG 21187: (CEO POA) Unknown addressee."; +****** End of administration information + +The Original Message is not available + + + +Hardcastle-Kille [Page 90] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + +5.3.9. Probe + + This is an MTS internal issue. Any probe shall be serviced by the + gateway, as there is no equivalent RFC 822 functionality. The value + of the reply is dependent on whether the gateway could service an MTS + Message with the values specified in the probe. The reply shall make + use of MTS.SupplementaryInformation to indicate that the probe was + serviced by the gateway. + +Appendix A - Mappings Specific to SMTP + + This Appendix is specific to the Simple Mail Transfer Protocol (RFC + 821). It describes specific changes in the context of this protocol. + When servicing a probe, as described in section 5.3.9, use may be + made of the SMTP VRFY command to increase the accuracy of information + contained in the delivery report. + +Appendix B - Mappings specific to the JNT Mail + + This Appendix is specific to the JNT Mail Protocol. It describes + specific changes in the context of this protocol. + + 1. Introduction + + There are five aspects of a gateway which are JNT Mail Specific. + These are each given a section of this appendix. + + 2. Domain Ordering + + When interpreting and generating domains, the UK NRS domain + ordering shall be used, both in headers, and in text generated for + human description. + + 3. Addressing + + A gateway which maps to JNT Mail should recognise the Domain + Defined Attribute JNT-MAIL. The value associated with this + attribute should be interpreted according to the JNT Mail + Specification. This DDA shall never be generated by a gateway. + For this reason, the overflow mechanism is not required. + + 4. Acknowledge-To: + + This field has no direct functional equivalent in X.400. However, + it can be supported to an extent, and can be used to improve X.400 + support. + + If an Acknowledge-To: field is present when going from JNT Mail to + + + +Hardcastle-Kille [Page 91] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + X.400, there are two different situations. The first case is + where there is one address in the Acknowledge-To: field, and it is + equal to the 822-MTS return address. In this case, the + MTS.PerRecipientSubmissionFields.originator-request-report.report + shall be set for each recipient, and the Acknowledge-To: field + discarded. Here, X.400 can provide the equivalent service. + + In all other cases two actions are taken. + + 1. Acknowledgement(s) may be generated by the gateway. The + text of these acknowledgements shall indicate that they are + generated by the gateway, and do not correspond to delivery. + + 2. The Acknowledge-To: field shall be passed as an extension + heading. + + When going from X.400 to JNT Mail, in cases where + MTA.PerRecipientMessageTransferFields.per-recipient-indicators. + originator-report bit is set for all recipients (i.e., there is a + user request for a positive delivery report for every recipeint), + generate an Acknowledge-To: field containing the + MTS.OtherMessageDeliveryFields.originator-name. Receipt + notification requests are not mapped onto Acknowledge-To:, as no + association can be guaranteed between IPMS and MTS level + addressing information. + + 5. Trace + + JNT Mail trace uses the Via: syntax. When going from JNT Mail to + X.400, a mapping similar to that for Received: is used. No + MTS.GlobalDomainIdentifier of the site making the trace can be + derived from the Via:, so a value for the gateway is used. The + trace text, including the "Via:", is unfolded, truncated to + MTS.ub-mta-name-length (32), and mapped to + MTA.InternalTraceInformationElement.mta-name. There is no JNT + Mail specific mapping for the reverse direction. + + 6. Timezone specification + + The extended syntax of zone defined in the JNT Mail Protocol shall + be used in the mapping of UTCTime defined in Chapter 3. + + 7. Lack of 822-MTS originator specification + + In JNT Mail the default mapping of the + MTS.OtherMessageDeliveryFields.originator-name is to the Sender: + field. This can cause a problem when going from X.400 to JNT Mail + if the mapping of IPMS.Heading has already generated a Sender: + + + +Hardcastle-Kille [Page 92] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + field. To overcome this, new extended JNT Mail field is defined. + This is chosen to align with the JNT recommendation for + interworking with full RFC 822 systems [Kille84b]. + + original-sender = "Original-Sender" ":" mailbox + + If an IPM has no IPMS.Heading.authorizing-users component and + IPMS.Heading.originator.formal-name is different from + MTS.OtherMessageDeliveryFields.originator-name, map + MTS.OtherMessageDeliveryFields.originator-name, onto the Sender: + field. + + If an IPM has a IPMS.Heading.authorizing-users component, and + IPMS.Heading.originator.formal-name is different from + MTS.OtherMessageDeliveryFields.originator-name, + MTS.OtherMessageDeliveryFields.originator-name is mapped onto the + Sender: field, and IPMS.Heading.originator mapped onto the + Original-Sender: field. + + In other cases the MTS.OtherMessageDeliveryFields.originator-name, + is already correctly represented. + +Appendix C - Mappings specific to UUCP Mail + + Gatewaying of UUCP and X.400 is handled by first gatewaying the UUCP + address into RFC 822 syntax (using RFC 976) and then gatewaying the + resulting RFC 822 address into X.400. For example, an X.400 address + + Country US + Organisation Xerox + Personal Name John Smith + + might be expressed from UUCP as + + inthop!gate!gatehost.COM!/C=US/O=Xerox/PN=John.Smith/ + + (assuming gate is a UUCP-ARPA gateway and gatehost.COM is an ARPA- + X.400 gateway) or + + inthop!gate!Xerox.COM!John.Smith + + (assuming that Xerox.COM and /C=US/O=Xerox/ are equivalent.) + + In the other direction, a UUCP address Smith@ATT.COM, integrated into + 822, would be handled as any other 822 address. A non-integrated + address such as inthop!dest!user might be handled through a pair of + gateways: + + + + +Hardcastle-Kille [Page 93] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + Country US + ADMD ATT + PRMD ARPA + Organisation GateOrg + RFC-822 inthop!dest!user@gatehost.COM + + or through a single X.400 to UUCP gateway: + + Country US + ADMD ATT + PRMD UUCP + Organisation GateOrg + RFC-822 inthop!dest!user + +Appendix D - Object Identifier Assignment + + An object identifier is needed for the extension IPMS element. The + following value shall be used. + + rfc-987-88 OBJECT IDENTIFIER ::= + {ccitt data(9) pss(2342) ucl(234219200300) rfc-987-88(200)} + + id-rfc-822-field-list OBJECT IDENTIFIER ::= {rfc987-88 field(1)} + +Appendix E - BNF Summary + + boolean = "TRUE" / "FALSE" + + + numericstring = *DIGIT + + + printablestring = *( ps-char ) + ps-restricted-char = 1DIGIT / 1ALPHA / " " / "'" / "+" + / "," / "-" / "." / "/" / ":" / "=" / "?" + ps-delim = "(" / ")" + ps-char = ps-delim / ps-restricted-char + + + ps-encoded = *( ps-restricted-char / ps-encoded-char ) + ps-encoded-char = "(a)" ; (@) + / "(p)" ; (%) + / "(b)" ; (!) + / "(q)" ; (") + / "(u)" ; (_) + / "(l)" ; "(" + / "(r)" ; ")" + / "(" 3DIGIT ")" + + + +Hardcastle-Kille [Page 94] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + teletex-string = *( ps-char / t61-encoded ) + t61-encoded = "{" 1* t61-encoded-char "}" + t61-encoded-char = 3DIGIT + + + teletex-and-or-ps = [ printablestring ] [ "*" teletex-string ] + + + labelled-integer ::= [ key-string ] "(" numericstring ")" + + key-string = *key-char + key-char = <a-z, A-Z, 0-9, and "-"> + + object-identifier ::= oid-comp object-identifier + | oid-comp + + oid-comp ::= [ key-string ] "(" numericstring ")" + + + encoded-info = 1#encoded-type + + encoded-type = built-in-eit / object-identifier + + built-in-eit = "Undefined" ; undefined (0) + / "Telex" ; tLX (1) + / "IA5-Text" ; iA5Text (2) + / "G3-Fax" ; g3Fax (3) + / "TIF0" ; tIF0 (4) + / "Teletex" ; tTX (5) + / "Videotex" ; videotex (6) + / "Voice" ; voice (7) + / "SFD" ; sFD (8) + / "TIF1" ; tIF1 (9) + + + + encoded-pn = [ given "." ] *( initial "." ) surname + + given = 2*<ps-char not including "."> + + initial = ALPHA + + surname = printablestring + + std-or-address = 1*( "/" attribute "=" value ) "/" + attribute = standard-type + / "RFC-822" + / registered-dd-type + + + +Hardcastle-Kille [Page 95] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + / dd-key "." std-printablestring + standard-type = key-string + + registered-dd-type + = key-string + dd-key = key-string + + value = std-printablestring + + std-printablestring + = *( std-char / std-pair ) + std-char = <"{", "}", "*", and any ps-char + except "/" and "="> + std-pair = "$" ps-char + + + dmn-or-address = dmn-part *( "." dmn-part ) + dmn-part = attribute "$" value + attribute = standard-type + / "~" dmn-printablestring + value = dmn-printablestring + / "@" + dmn-printablestring = + = *( dmn-char / dmn-pair ) + dmn-char = <"{", "}", "*", and any ps-char + except "."> + dmn-pair = "\." + + + global-id = std-or-address + + + + mta-field = "X400-Received" ":" x400-trace + / "Deferred-Delivery" ":" date-time + / "Latest-Delivery-Time" ":" date-time + + x400-trace = "by" md-and-mta ";" + [ "deferred until" date-time ";" ] + [ "converted" "(" encoded-info ")" ";" ] + [ "attempted" md-or-mta ";" ] + action-list + ";" arrival-time + + + md-and-mta = [ "mta" mta "in" ] global-id + mta = word + arrival-time = date-time + + + +Hardcastle-Kille [Page 96] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + md-or-mta = "MD" global-id + / "MTA" mta + + Action-list = 1#action + action = "Redirected" + / "Expanded" + / "Relayed" + / "Rerouted" + + dr-body-format = dr-summary <CRLF> + dr-recipients <CRLF> + dr-administrator-info-envelope <CRLF> + dr-content-return + + + dr-content-return = "The Original Message is not available" + / "The Original Message follows:" + + dr-summary = "This report relates to your message:" <CRLF> + content-correlator <CRLF> <CRLF> + "of" date-time <CRLF> <CRLF> + + + dr-recipients = *(dr-recipient <CRLF> <CRLF>) + + dr-recipient = dr-recip-success / dr-recip-failure + + dr-recip-success = + "Your message was successfully delivered to:" + mailbox "at" date-time + + + dr-recip-failure = "Your message was not delivered to:" + mailbox <CRLF> + "for the following reason:" *word + + + dr-administrator-info-envelope = 3*( "*" text <CRLF> ) + + + dr-administrator-info = + "**** The following information is directed towards" + "the local administrator" <CRLF> + "**** and is not intended for the end user" <CRLF> <CRLF> + "DR generated by:" report-point <CRLF> + "at" date-time <CRLF> <CRLF> + "Converted to RFC 822 at" mta <CRLF> + "at" date-time <CRLF> <CRLF> + + + +Hardcastle-Kille [Page 97] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + "Delivery Report Contents:" <CRLF> <CRLF> + drc-field-list <CRLF> + "***** End of administration information" + + drc-field-list = *(drc-field <CRLF>) + + drc-field = "Subject-Submision-Identifier" ":" + mts-msg-id + / "Content-Identifier" ":" printablestring + / "Content-Type" ":" mts-content-type + / "Original-Encoded-Information-Types" ":" + encoded-info + / "Originator-and-DL-Expansion-History" ":" + dl-history + / "Reporting-DL-Name" ":" mailbox + / "Content-Correlator" ":" content-correlator + / "Recipient-Info" ":" recipient-info + / "Subject-Intermediate-Trace-Information" ":" + x400-trace + + + recipient-info = mailbox "," std-or ";" + report-type + [ "converted eits" encoded-info ";" ] + [ "originally intended recipient" + mailbox "," std-or ";" ] + [ "last trace" [ encoded-info ] date-time ";" ] + [ "supplementary info" <"> printablestring <"> ";" ] + [ "redirection history" 1#redirection ";" + [ "physical forwarding address" + printablestring ";" ] + + + report-type = "SUCCESS" drc-success + / "FAILURE" drc-failure + + drc-success = "delivered at" date-time ";" + [ "type of MTS user" labelled-integer ";" ] + + drc-failure = "reason" labelled-integer ";" + [ "diagnostic" labelled-integer ";" ] + + + report-point = [ "mta" word "in" ] global-id + content-correlator = *word + dl-history = 1#( mailbox "(" date-time ")") + + + + + +Hardcastle-Kille [Page 98] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + mts-field = "X400-MTS-Identifier" ":" mts-msg-id + / "X400-Originator" ":" mailbox + / "X400-Recipients" ":" 1#mailbox + / "Original-Encoded-Information-Types" ":" + encoded-info + / "X400-Content-Type" ":" mts-content-type + / "Content-Identifier" ":" printablestring + / "Priority" ":" priority + / "Originator-Return-Address" ":" 1#mailbox + / "DL-Expansion-History" ":" mailbox ";" date-time ";" + / "Conversion" ":" prohibition + / "Conversion-With-Loss" ":" prohibition + / "Requested-Delivery-Method" ":" + 1*( labelled-integer ) + / "Delivery-Date" ":" date-time + / "Discarded-X400-MTS-Extensions" ":" + 1#( oid / labelled-integer ) + + + prohibition = "Prohibited" / "Allowed" + + mts-msg-id = "[" global-id ";" *text "]" + + mts-content-type = "P2" / labelled-integer + / object-identifer + + priority = "normal" / "non-urgent" / "urgent" + + ipn-body-format = ipn-description <CRLF> + [ ipn-extra-information <CRLF> ] + [ ipn-content-return ] + + ipn-description = ipn-receipt / ipn-non-receipt + + ipn-receipt = "Your message to:" preferred-recipient <CRLF> + "was received at" receipt-time <CRLF> <CRLF> + "This notification was generated" + acknowledgement-mode <CRLF> + "The following extra information was given:" <CRLF> + ipn-suppl <CRLF> + + ipn-non-receipt "Your message to:" + preferred-recipient <CRLF> + ipn-reason + + + ipn-reason = ipn-discarded / ipn-auto-forwarded + + + + +Hardcastle-Kille [Page 99] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + ipn-discarded = "was discarded for the following reason:" + discard-reason <CRLF> + + ipn-auto-forwarded = "was automatically forwarded." <CRLF> + [ "The following comment was made:" + auto-comment ] + + + ipn-extra-information = + "The following information types were converted:" + encoded-info + + ipn-content-return = "The Original Message is not available" + / "The Original Message follows:" + <CRLF> <CRLF> message + + + preferred-recipient = mailbox + receipt-time = date-time + auto-comment = printablestring + ipn-suppl = printablestring + + discard-reason = "Expired" / "Obsoleted" / + "User Subscription Terminated" + + acknowledgement-mode = "Manually" / "Automatically" + + + ipms-field = "Obsoletes" ":" 1#msg-id + / "Expiry-Date" ":" date-time + / "Reply-By" ":" date-time + / "Importance" ":" importance + / "Sensitivity" ":" sensitivity + / "Autoforwarded" ":" boolean + / "Incomplete-Copy" ":" + / "Language" ":" language + / "Message-Type" ":" message-type + / "Discarded-X400-IPMS-Extensions" ":" 1#oid + + + + importance = "low" / "normal" / "high" + + + sensitivity = "Personal" / "Private" / + "Company-Confidential" + + language = 2*ALPHA [ language-description ] + + + +Hardcastle-Kille [Page 100] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + language-description = printable-string + + + + message-type = "Delivery Report" + / "InterPersonal Notification" + / "Multiple Part" + + redirect-comment = + [ "Originally To:" ] mailbox "Redirected" + [ "Again" ] "on" date-time + "To:" redirection-reason + + redirection-reason = + "Recipient Assigned Alternate Recipient" + / "Originator Requested Alternate Recipient" + / "Recipient MD Assigned Alternate Recipient" + + + subject-line = "Delivery-Report" "(" status ")" + [ "for" destination ] + + status = "success" / "failure" / "success and failures" + + destination = mailbox / "MTA" word + + + extended-heading = + "Prevent-NonDelivery-Report" ":" + / "Generate-Delivery-Report" ":" + / "Alternate-Recipient" ":" prohibition + / "Disclose-Recipients" ":" prohibition + / "Content-Return" ":" prohibition + +Appendix F - Format of address mapping tables + + 1. Global Mapping Information + + The consistent operation of gateways which follow this + specification relies of the existence of three globally defined + mappings: + + 1. Domain Name Space -> O/R Address Space + + 2. O/R Address Space -> Domain Name Space + + 3. Domain Name Space -> O/R Address of preferred gateway + + + + +Hardcastle-Kille [Page 101] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + All gateways conforming to this specification shall have access to + these mappings. The gateway may use standardised or private + mechanisms to access this mapping information. + + One means of distributing this information is in three files. + This appendix defines a format for these files. Other + standardised mechanisms to distribute the mapping information are + expected. In particular, mechanisms for using the Domain Name + Scheme, and X.500 are planned. + + The definition of global mapping information is being co- + ordinated by the COSINE-MHS project, on behalf of the Internet and + other X.400 and RFC 822 users. For information on accessing this + information contact: + + COSINE MHS Project Team + SWITCH + Weinbergstrasse 18 + 8001 Zuerich + Switzerland + + tel: +41 1 262 3143 + fax: +41 1 262 3151 + email: + C=ch;ADMD=arcom;PRMD=switch;O=switch;OU=cosine-mhs; + S=project-team + or + project-team@cosine-mhs.switch.ch + + 2. Syntax Definitions + + An address syntax is defined, which is compatible with the syntax + used for 822.domains. By representing the O/R addresses as + domains, all lookups can be mechanically implemented as domain -> + domain mappings. This syntax defined is initially for use in + table format, but the syntax is defined in a manner which makes it + suitable to be adapted for use with the Domain Name Service. + This syntax allows for a general representation of O/R addresses, + so that it can be used in other applications. Not all attributes + are used in the table formats defined. + + To allow the mapping of null attributes to be represented, the + pseudo-value "@" (not a printable string character) is used to + indicate omission of a level in the hierarchy. This is distinct + from the form including the element with no value, although a + correct X.400 implementation will interpret both in the same + manner. + + + + +Hardcastle-Kille [Page 102] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + This syntax is not intended to be handled by users. + + dmn-or-address = dmn-part *( "." dmn-part ) + dmn-part = attribute "$" value + attribute = standard-type + / "~" dmn-printablestring + value = dmn-printablestring + / "@" + dmn-printablestring = + = *( dmn-char / dmn-pair ) + dmn-char = <"{", "}", "*", and any ps-char + except "."> + dmn-pair = "\." + + An example usage: + + ~ROLE$Big\.Chief.ADMD$ATT.C$US + PRMD$DEC.ADMD$@.C$US + + The first example illustrates quoting of a ".", and the second + omission of the ADMD level. There must be a strict ordering of all + components in this table, with the most significant components on + the RHS. This allows the encoding to be treated as a domain. + + Various further restrictions are placed on the usage of dmn-or- + address in the address space mapping tables. + + 1. Only C, ADMD, PRMD, O, and up to four OUs may be used. + + 2. No components shall be omitted from this hierarchy, although + the hierarchy may terminate at any level. If the mapping is + to an omitted component, the "@" syntax is used. + + 3. Table Lookups + + When determining a match, there are aspects which apply to all + lookups. Matches are always case independent. The key for all + three tables is a domain. The longest possible match shall be + obtained. Suppose the table has two entries with the following + keys: + + K.L + J.K.L + + Domain "A.B.C" will not return any matches. Domain "I.J.K.L" will + match the entry "J.K.L:. + + + + + +Hardcastle-Kille [Page 103] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + 4. Domain -> O/R Address format + + The BNF is: + + domain-syntax "#" dmn-or-address "#" + + Note that the trailing "#" is used for clarity, as the dmn-or- + address syntax might lead to values with trailing blanks. Lines + staring with "#" are comments. + + For example: + AC.UK#PRMD$UK\.AC.ADMD$GOLD 400.C$GB# + XEROX.COM#O$Xerox.ADMD$ATT.C$US# + GMD.DE#O$@.PRMD$GMD.ADMD$DBP.C$DE# + + A domain is looked up to determine the top levels of an O/R + Address. Components of the domain which are not matched are used + to build the remainder of the O/R address, as described in Section + 4.3.4. + + 5. O/R Address -> Domain format + + The syntax of this table is: + + dmn-or-address "#" domain-syntax "#" + + + For example: + + # + # Mapping table + # + PRMD$UK\.AC.ADMD$GOLD 400.C$GB#AC.UK# + + The O/R Address is used to generate a domain key. It is important + to order the components correctly, and to fill in missing + components in the hierarchy. Use of this mapping is described in + Section 4.3.2. + + 6. Domain -> O/R Address of Gateway table + + This uses the same format as the domain -> O/R address mapping. + In this case, the two restrictions (omitted components and + restrictions on components) do not apply. Use of this mapping is + described in Section 4.3.4. + + + + + + +Hardcastle-Kille [Page 104] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + +Appendix G - Mapping with X.400(1984) + + This appendix defines modification to the mapping for use with + X.400(1984). + + The X.400(1984) protocols are a proper subset of X.400(1988). When + mapping from X.400(1984) to RFC 822, no changes to this specification + are needed. + + When mapping from RFC 822 to X.400(1984), no use can be made of 1988 + specific features. No use of such features is made at the MTS + level. One feature is used at the IPMS level, and this must be + replaced by the RFC 987 approach. All header information which would + usually be mapped into the rfc-822-heading-list extension, together + with any Comments: field in the RFC 822 header is mapped into a + single IA5 body part, which is the first body part in the message. + This body part will start with the string "RFC-822-Headers:" as the + first line. The headers then follow this line. This specification + requires correct reverse mapping of this format, either from 1988 or + 1984. + + In an environment where RFC 822 is of major importance, it may be + desirable for downgrading to consider the case where the message was + originated in an RFC 822 system, and mapped according to this + specification. The rfc-822-heading-list extension may be mapped + according to this appendix. + + When parsing std-or, the following restrictions must be observed: + + - Only the 84/88 attributes identified in the table in + Section 4.2 are present. + + - No teletex encoding is allowed. + + If an address violates this, it should be treated as an RFC 822 + address, which will usually lead to encoding as a DDA "RFC-822". + + It is possible that null attributes may be present in an O/R Address. + This is not legal in 1988, except for ADMD where the case is + explicitly described in Section 4.3.5. Null attributes are + deprecated (the attribute should be omitted), and should therefore be + unusual. However, some systems generate them and rely on them. + Therefore, any null attribute shall be enoded using the std-or + encoding (e.g., /O=/). + + If a non-Teletex Common Name (CN) is present, it should be mapped + onto a Domain Defined Attribute "Common". This is in line with RFC + 1328 on X.400 1988 to 1984 downgrading [Hardcastle-K92]. + + + +Hardcastle-Kille [Page 105] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + +Appendix H - RFC 822 Extensions for X.400 access + + This appendix defines a number of optional mappings which may be + provided to give access from RFC 822 to a number of X.400 services. + These mappings are beyond the basic scope of this specification. + There has been a definite demand to use extended RFC 822 as a + mechanism to acccess X.400, and these extensions provide access to + certain features. If this functionality is provided, this appendix + shall be followed. The following headings are defined: + + extended-heading = + "Prevent-NonDelivery-Report" ":" + / "Generate-Delivery-Report" ":" + / "Alternate-Recipient" ":" prohibition + / "Disclose-Recipients" ":" prohibition + / "Content-Return" ":" prohibition + + Prevent-NonDelivery-Report and Generate-Delivery-Report allow setting + of MTS.PerRecipientSubmissionFields.originator-report-request. The + setting will be the same for all recipients. + + Alternate-Recipient, Disclose-Recipients, and Content-Return allow + for override of the default settings for MTS.PerMessageIndicators. + +Appendix I - Conformance + + This appendix defines a number of options, which a conforming gateway + should specify. Conformance to this specification shall not be + claimed if any of the mandatory features are not implemented. In + particular: + + - Formats for all fields shall be followed. + + - Formats for subject lines, delivery reports and IPNs shall + be followed. A system which followed the syntax, but + translated text into a language other than english would be + conformant. + + - RFC 1137 shall not be followed when mapping to SMTP or to + JNT Mail + + - All mappings of trace shall be implemented. + + - There must be a mechanism to access all three global + mappings. + + A gateway should specify: + + + + +Hardcastle-Kille [Page 106] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + - Which 822-MTS protocols are supported. The relevant + appendices must be followed to claim support of a given + protocol: SMTP (A); JNT Mail (B); UUCP (C). + + - Which X.400 versions are supported (84 and/or 88). + + - The means by which it can access the global mappings. + Currently, the tables of the formats define in Appendix F + is the only means available. + + - The approach taken when upper bounds are exceeded at the IPM + level (5.1.3) + + - The approach taken to return of contents (5.2) + + - The approach taken to body parts which cannot be converted + (5.3.4) + + - The approach taken to multiple copies vs non-disclosure + (4.6.2.2) + + The following are optional parts of this specification. A conforming + implementation should specify which of these it supports. + + - Generation of extended RFC 822 fields is mandatory. + Optionally, they may be parsed and mapped back to X.400. A + gateway should should indicate if this is done. + + - Support for the extension mappings of Appendix H. + + - Support for returning illegal format content in a delivery + report + + - Which address interpretation heuristics are supported + (4.3.4.1) + + - If RFC 987 generated message ids are handled in a backwards + compatible manner (4.7.3.6) + +Appendix J - Change History: RFC 987, 1026, 1138, 1148 + + RFC 987 was the original document, and contained the key elements of + this specification. It was specific to X.400(1984). RFC 1026 + specified a small number of necessary changes to RFC 987. + + RFC 1138 was based on the RFC 987 work. It contained an editorial + error, and was reissued a few months later as RFC 1148. RFC 1148 + will be referred to here, as it is the document which is widely + + + +Hardcastle-Kille [Page 107] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + referred to elsewhere. The major goal of RFC 1148 was to upgrade RFC + 987 to X.400(1988). It did this, but did not obsolete RFC 987, which + was recommended for use with X.400(1984). This appendix summarises + the changes made in going from RFC 987 to RFC 1148. + + RFC 1148 noted the following about its upgrade from RFC 987: + Unnecessary change is usually a bad idea. Changes on the RFC 822 + side are avoided as far as possible, so that RFC 822 users do not + see arbitrary differences between systems conforming to this + specification, and those following RFC 987. Changes on the X.400 + side are minimised, but are more acceptable, due to the mapping onto + a new set of services and protocols. + + 1. Introduction + + The model has shifted from a protocol based mapping to a service + based mapping. This has increased the generality of the + specification, and improved the model. This change affects the + entire document. + + A restriction on scope has been added. + + 2. Service Elements + + - The new service elements of X.400 are dealt with. + + - A clear distinction is made between origination and + reception + + 3. Basic Mappings + + - Add teletex support + + - Add object identifier support + + - Add labelled integer support + + - Make PrintableString <-> ASCII mapping reversible + + - The printable string mapping is aligned to the NBS mapping + derived from RFC 987. + + 4. Addressing + + - Support for new addressing attributes + + - The message ID mapping is changed to not be table driven + + + + +Hardcastle-Kille [Page 108] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + 5. Detailed Mappings + + - Define extended IPM Header, and use instead of second body + part for RFC 822 extensions + + - Realignment of element names + + - New syntax for reports, simplifying the header and + introducing a mandatory body format (the RFC 987 header + format was unusable) + + - Drop complex autoforwarded mapping + + - Add full mapping for IP Notifications, defining a body + format + + - Adopt an MTS Identifier syntax in line with the O/R Address + syntax + + - A new format for X400 Trace representation on the RFC 822 + side + + 6. Appendices + + - Move Appendix on restricted 822 mappings to a separate RFC + + - Delete Phonenet and SMTP Appendixes + +Appendix K - Change History: RFC 1148 to this Document + + 1. General + + - The scope of the document was changed to cover X.400(1984), + and so obsolete RFC 987. + + - Changes were made to allow usage to connect RFC 822 networks + using X.400 + + - Text was tightened to be clear about optional and mandatory + aspects + + - A good deal of clarification + + - A number of minor EBNF errors + + - Better examples are given + + - Further X.400 upper bounds are handled correctly + + + +Hardcastle-Kille [Page 109] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + 2. Basic Mappings + + - The encoding of object identifier is changed slightly + + 3. Addressing + + - A global mapping of domain to preferred gateway is + introduced. + + - An overflow mechanism is defined for RFC 822 addresses of + greater than 128 bytes. + + - Changes were made to improve compatability with the PDAM on + writing O/R Addresses. + + + The PD and Terminal Type keywords were aligned to the + PDAM. It is believed that minimal use has been made of + the RFC 1148 keywords. + + + P and A are allowed as alternate keys for PRMD and ADMD + + + Where keywords are different, the PDAM keywords are + alternatives on input. This is mandatory. + + 4. Detailed Mappings + + - The format of the Subject: lines is defined. + + - Illegal use (repetition) of the heading EXTENSION is + corrected, and a new object identifier assigned. + + - The Delivery Report format is extensively revised in light + of operational experience. + + - The handling of redirects is significantly changed, as the + previous mechanism did not work. + + 5. Appendices + + - An SMTP appendix is added, allowing optional use of the VRFY + command to improve probe information. + + - Handling of JNT Mail Acknowledge-To is changed slightly. + + - A DDA JNT-MAIL is allowed on input. + + - The format definitions of Appendix F are explained further, + and a third table definition added. + + + +Hardcastle-Kille [Page 110] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + - An appendix on use with X.400(1984) is added. + + - Optional extensions are defined to give RFC 822 access to + further X.400 facilities. + + - An appendix on conformance is added. + +References + + CCITT88a. + CCITT, "CCITT Recommendations X.408," Message Handling + Systems: Encoded Information Type Conversion Rules, December + 1988. + + CCITT/ISO88a. + CCITT/ISO, "CCITT Recommendations X.400/ ISO IS 10021-1," + Message Handling: System and Service Overview , December + 1988. + + CCITT/ISO88b. + CCITT/ISO, "CCITT Recommendations X.420/ ISO IS 10021-7," + Message Handling Systems: Interpersonal Messaging System, + December 1988. + + CCITT/ISO88c. + CCITT/ISO, "CCITT Recommendations X.411/ ISO IS 10021-4," + Message Handling Systems: Message Transfer System: Abstract + Service Definition and Procedures, December 1988. + + CCITT/ISO88d. + CCITT/ISO, "Specification of Abstract Syntax Notation One + (ASN.1)," CCITT Recommendation X.208 / ISO IS 8824, December + 1988. + + CCITT/ISO91a. + CCITT/ISO, "Representation of O/R Addresses for Human + Usage," PDAM to CCITT X.401 / ISO/IEC 10021-2, February + 1991. + + Crocker82a. + Crocker, D., "Standard of the Format of ARPA Internet Text + Messages," RFC 822, UDEL, August 1982. + + Hardcastle-K92. + Hardcastle-Kille, S., "X.400 1988 to 1984 downgrading," RFC + 1328, UCL, May 1992. + + + + + +Hardcastle-Kille [Page 111] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + Horton86a. + Horton, M., "UUCP Mail Interchange Format Standard," RFC + 976, February 1986. + + Kille84b. + Kille, S., "Gatewaying between RFC 822 and JNT Mail," JNT + Mailgroup Note 15, May 1984. + + Kille84a. + Kille, S., (Editor), JNT Mail Protocol (revision 1.0), Joint + Network Team, Rutherford Appleton Laboratory, March 1984. + + Kille86a. + Kille, S., "Mapping Between X.400 and RFC 822," UK Academic + Community Report (MG.19) / RFC 987, June 1986. + + Kille87a. + Kille, S., "Addendum to RFC 987," UK Academic Community + Report (MG.23) / RFC 1026, August 1987. + + Kille89a. + Kille, S., "A String Encoding of Presentation Address," UCL + Research Note 89/14, March 1989. + + Kille89b. + Kille, S., "Mapping between full RFC 822 and RFC 822 with + restricted encoding," RFC 1137, October 1989. + + Kille90a. + Kille, S., "Mapping Between X.400(1988) / ISO 10021 and RFC + 822," RFC 1148, March 1990. + + Larmouth83a. + Larmouth, J., "JNT Name Registration Technical Guide," + Salford University Computer Centre, April 1983. + + Postel84a. + Postel J., and J. Reynolds, "Domain Requirements," RFC 920, + USC/Information Sciences Institute, October 1984. + + Postel82a. + Postel, J., "Simple Mail Transfer Protocol", RFC 821, + USC/Information Sciences Institute, August 1982. + + Rose85a. + Rose M., and E. Stefferud, "Proposed Standard for Message + Encapsulation," RFC 934, January 1985. + + + + +Hardcastle-Kille [Page 112] + +RFC 1327 Mapping between X.400(1988) and RFC 822 May 1992 + + + Systems85a. + CEN/CENELEC/Information Technology/Working Group on Private + Message Handling Systems, "FUNCTIONAL STANDARD A/3222," + CEN/CLC/IT/WG/PMHS N 17, October 1985. + +SECURITY CONSIDERATIONS + + Security issues are not discussed in this memo. + +AUTHOR'S ADDRESS + + Steve Hardcastle-Kille + Department of Computer Science + University College London + Gower Street + WC1E 6BT + England + + Phone: +44-71-380-7294 + EMail: S.Kille@CS.UCL.AC.UK + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Hardcastle-Kille [Page 113] +
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