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diff --git a/doc/rfc/rfc4021.txt b/doc/rfc/rfc4021.txt new file mode 100644 index 0000000..f72de3f --- /dev/null +++ b/doc/rfc/rfc4021.txt @@ -0,0 +1,3027 @@ + + + + + + +Network Working Group G. Klyne +Request for Comments: 4021 University of Oxford +Category: Standards Track J. Palme + Stockholm University/KT + March 2005 + + + Registration of Mail and MIME Header Fields + +Status of This Memo + + This document specifies an Internet standards track protocol for the + Internet community, and requests discussion and suggestions for + improvements. Please refer to the current edition of the "Internet + Official Protocol Standards" (STD 1) for the standardization state + and status of this protocol. Distribution of this memo is unlimited. + +Copyright Notice + + Copyright (C) The Internet Society (2005). + +Abstract + + This document defines the initial IANA registration for permanent + mail and MIME message header fields, per RFC 3864. + +Table of Contents + 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 + 1.1. Structure of This Document . . . . . . . . . . . . . . . 3 + 1.2. Document Terminology and Conventions . . . . . . . . . . 4 + 2. Registration Templates . . . . . . . . . . . . . . . . . . . . 4 + 2.1. Permanent Mail Header Field Registrations . . . . . . . 4 + 2.1.1. Header Field: Date . . . . . . . . . . . . . . . 6 + 2.1.2. Header Field: From . . . . . . . . . . . . . . . 7 + 2.1.3. Header Field: Sender . . . . . . . . . . . . . . 7 + 2.1.4. Header Field: Reply-To . . . . . . . . . . . . . 8 + 2.1.5. Header Field: To . . . . . . . . . . . . . . . . 8 + 2.1.6. Header Field: Cc . . . . . . . . . . . . . . . . 9 + 2.1.7. Header Field: Bcc . . . . . . . . . . . . . . . 9 + 2.1.8. Header Field: Message-ID . . . . . . . . . . . . 10 + 2.1.9. Header Field: In-Reply-To . . . . . . . . . . . 10 + 2.1.10. Header Field: References . . . . . . . . . . . . 11 + 2.1.11. Header Field: Subject . . . . . . . . . . . . . 11 + 2.1.12. Header Field: Comments . . . . . . . . . . . . . 12 + 2.1.13. Header Field: Keywords . . . . . . . . . . . . . 12 + 2.1.14. Header Field: Resent-Date . . . . . . . . . . . 13 + 2.1.15. Header Field: Resent-From . . . . . . . . . . . 13 + 2.1.16. Header Field: Resent-Sender . . . . . . . . . . 14 + + + +G. Klyne, et al. Standards Track [Page 1] + +RFC 4021 Mail and MIME Header Fields March 2005 + + + 2.1.17. Header Field: Resent-To . . . . . . . . . . . . 14 + 2.1.18. Header Field: Resent-Cc . . . . . . . . . . . . 15 + 2.1.19. Header Field: Resent-Bcc . . . . . . . . . . . . 15 + 2.1.20. Header Field: Resent-Reply-To . . . . . . . . . 16 + 2.1.21. Header Field: Resent-Message-ID . . . . . . . . 16 + 2.1.22. Header Field: Return-Path . . . . . . . . . . . 17 + 2.1.23. Header Field: Received . . . . . . . . . . . . . 17 + 2.1.24. Header Field: Encrypted . . . . . . . . . . . . 18 + 2.1.25. Header Field: Disposition-Notification-To . . . 18 + 2.1.26. Header Field: Disposition-Notification-Options . 19 + 2.1.27. Header Field: Accept-Language . . . . . . . . . 19 + 2.1.28. Header Field: Original-Message-ID . . . . . . . 20 + 2.1.29. Header Field: PICS-Label . . . . . . . . . . . . 20 + 2.1.30. Header Field: Encoding . . . . . . . . . . . . . 21 + 2.1.31. Header Field: List-Archive . . . . . . . . . . . 21 + 2.1.32. Header Field: List-Help . . . . . . . . . . . . 22 + 2.1.33. Header Field: List-ID . . . . . . . . . . . . . 22 + 2.1.34. Header Field: List-Owner . . . . . . . . . . . . 23 + 2.1.35. Header Field: List-Post . . . . . . . . . . . . 23 + 2.1.36. Header Field: List-Subscribe . . . . . . . . . . 24 + 2.1.37. Header Field: List-Unsubscribe . . . . . . . . . 24 + 2.1.38. Header Field: Message-Context . . . . . . . . . 25 + 2.1.39. Header Field: DL-Expansion-History . . . . . . . 25 + 2.1.40. Header Field: Alternate-Recipient . . . . . . . 26 + 2.1.41. Header Field: Original-Encoded-Information-Types 26 + 2.1.42. Header Field: Content-Return . . . . . . . . . . 27 + 2.1.43. Header Field: Generate-Delivery-Report . . . . . 27 + 2.1.44. Header Field: Prevent-NonDelivery-Report . . . . 28 + 2.1.45. Header Field: Obsoletes . . . . . . . . . . . . 28 + 2.1.46. Header Field: Supersedes . . . . . . . . . . . . 29 + 2.1.47. Header Field: Content-Identifier . . . . . . . . 29 + 2.1.48. Header Field: Delivery-Date . . . . . . . . . . 30 + 2.1.49. Header Field: Expiry-Date . . . . . . . . . . . 30 + 2.1.50. Header Field: Expires . . . . . . . . . . . . . 31 + 2.1.51. Header Field: Reply-By . . . . . . . . . . . . . 31 + 2.1.52. Header Field: Importance . . . . . . . . . . . . 32 + 2.1.53. Header Field: Incomplete-Copy . . . . . . . . . 32 + 2.1.54. Header Field: Priority . . . . . . . . . . . . . 33 + 2.1.55. Header Field: Sensitivity . . . . . . . . . . . 33 + 2.1.56. Header Field: Language . . . . . . . . . . . . . 34 + 2.1.57. Header Field: Conversion . . . . . . . . . . . . 34 + 2.1.58. Header Field: Conversion-With-Loss . . . . . . . 35 + 2.1.59. Header Field: Message-Type . . . . . . . . . . . 35 + 2.1.60. Header Field: Autosubmitted . . . . . . . . . . 36 + 2.1.61. Header Field: Autoforwarded . . . . . . . . . . 36 + 2.1.62. Header Field: Discarded-X400-IPMS-Extensions . . 37 + 2.1.63. Header Field: Discarded-X400-MTS-Extensions . . 37 + 2.1.64. Header Field: Disclose-Recipients . . . . . . . 38 + + + +G. Klyne, et al. Standards Track [Page 2] + +RFC 4021 Mail and MIME Header Fields March 2005 + + + 2.1.65. Header Field: Deferred-Delivery . . . . . . . . 38 + 2.1.66. Header Field: Latest-Delivery-Time . . . . . . . 39 + 2.1.67. Header Field: Originator-Return-Address . . . . 39 + 2.1.68. Header Field: X400-Content-Identifier . . . . . 40 + 2.1.69. Header Field: X400-Content-Return . . . . . . . 40 + 2.1.70. Header Field: X400-Content-Type . . . . . . . . 41 + 2.1.71. Header Field: X400-MTS-Identifier . . . . . . . 41 + 2.1.72. Header Field: X400-Originator . . . . . . . . . 42 + 2.1.73. Header Field: X400-Received . . . . . . . . . . 42 + 2.1.74. Header Field: X400-Recipients . . . . . . . . . 43 + 2.1.75. Header Field: X400-Trace . . . . . . . . . . . . 43 + 2.2. Permanent MIME Header Field Registrations . . . . . . . 44 + 2.2.1. Header Field: MIME-Version . . . . . . . . . . . 44 + 2.2.2. Header Field: Content-ID . . . . . . . . . . . . 45 + 2.2.3. Header Field: Content-Description . . . . . . . 45 + 2.2.4. Header Field: Content-Transfer-Encoding . . . . 46 + 2.2.5. Header Field: Content-Type . . . . . . . . . . . 46 + 2.2.6. Header Field: Content-Base . . . . . . . . . . . 47 + 2.2.7. Header Field: Content-Location . . . . . . . . . 47 + 2.2.8. Header Field: Content-features . . . . . . . . . 48 + 2.2.9. Header Field: Content-Disposition . . . . . . . 48 + 2.2.10. Header Field: Content-Language . . . . . . . . . 49 + 2.2.11. Header Field: Content-Alternative . . . . . . . 49 + 2.2.12. Header Field: Content-MD5 . . . . . . . . . . . 50 + 2.2.13. Header Field: Content-Duration . . . . . . . . . 50 + 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 50 + 4. Security Considerations . . . . . . . . . . . . . . . . . . . 51 + 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 51 + 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 51 + 6.1. Normative References . . . . . . . . . . . . . . . . . . 51 + 6.2. Informative References . . . . . . . . . . . . . . . . . 53 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 53 + Full Copyright Statement . . . . . . . . . . . . . . . . . . . . . 54 + +1. Introduction + + This document defines IANA registration for a number of mail message + and MIME header fields, per registration procedures for message + header fields [1]. + + The main body of this document is automatically generated from RDF/N3 + data. Some experimental HTML registry pages have been prepared from + the same data and can be found at [27]. + +1.1. Structure of This Document + + Section 2.1 contains the templates for initial registration of mail + message header fields. + + + +G. Klyne, et al. Standards Track [Page 3] + +RFC 4021 Mail and MIME Header Fields March 2005 + + + Section 2.2 contains templates for initial registration of MIME + header fields. + +1.2. Document Terminology and Conventions + + The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", + "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this + document are to be interpreted as described in BCP 14, RFC 2119 [9]. + +2. Registration Templates + + Header field registry entries are summarized in tabular form for + convenience of reference and presented in full in the following + sections. + +2.1. Permanent Mail Header Field Registrations + + + Header name Protocol + ----------- -------- + Date Mail Message date and time + From Mail Mailbox of message author + Sender Mail Mailbox of message sender + Reply-To Mail Mailbox for replies to message + To Mail Primary recipient mailbox + Cc Mail Carbon-copy recipient mailbox + Bcc Mail Blind-carbon-copy recipient + mailbox + Message-ID Mail Message identifier + In-Reply-To Mail Identify replied-to message(s) + References Mail Related message identifier(s) + Subject Mail Topic of message + Comments Mail Additional comments about the + message + Keywords Mail Message key words and/or phrases + Resent-Date Mail Date and time message is resent + Resent-From Mail Mailbox of person for whom message + is resent + Resent-Sender Mail Mailbox of person who actually + resends the message + Resent-To Mail Mailbox to which message is resent + Resent-Cc Mail Mailbox(es) to which message is + cc'ed on resend + Resent-Bcc Mail Mailbox(es) to which message is + bcc'ed on resend + Resent-Reply-To Mail Resent reply-to + Resent-Message-ID Mail Message identifier for resent + message + + + +G. Klyne, et al. Standards Track [Page 4] + +RFC 4021 Mail and MIME Header Fields March 2005 + + + Return-Path Mail Message return path + Received Mail Mail transfer trace information + Encrypted Mail Message encryption information + Disposition-Notification-To + Mail Mailbox for sending disposition + notification + Disposition-Notification-Options + Mail Disposition notification options + Accept-Language Mail Language(s) for auto-responses + Original-Message-ID Mail Original message identifier + PICS-Label Mail PICS rating label + Encoding Mail Message encoding and other + information + List-Archive Mail URL of mailing list archive + List-Help Mail URL for mailing list information + List-ID Mail Mailing list identifier + List-Owner Mail URL for mailing list owner's + mailbox + List-Post Mail URL for mailing list posting + List-Subscribe Mail URL for mailing list subscription + List-Unsubscribe Mail URL for mailing list + unsubscription + Message-Context Mail Type or context of message + DL-Expansion-History + Mail Trace of distribution lists passed + Alternate-Recipient Mail Controls forwarding to alternate + recipients + Original-Encoded-Information-Types + Mail Body part types in message + Content-Return Mail Return content on non-delivery? + Generate-Delivery-Report + Mail Request delivery report generation + Prevent-NonDelivery-Report + Mail Non-delivery report required? + Obsoletes Mail Reference message to be replaced + Supersedes Mail Reference message to be replaced + Content-Identifier Mail Message content identifier + Delivery-Date Mail Message delivery time + Expiry-Date Mail Message expiry time + Expires Mail Message expiry time + Reply-By Mail Time by which a reply is requested + Importance Mail Message importance + Incomplete-Copy Mail Body parts are missing + Priority Mail Message priority + Sensitivity Mail Message content sensitivity + Language Mail X.400 message content language + Conversion Mail Conversion allowed? + + + + +G. Klyne, et al. Standards Track [Page 5] + +RFC 4021 Mail and MIME Header Fields March 2005 + + + Conversion-With-Loss + Mail Lossy conversion allowed? + Message-Type Mail Message type: delivery report? + Autosubmitted Mail Automatically submitted indicator + Autoforwarded Mail Automatically forwarded indicator + Discarded-X400-IPMS-Extensions + Mail X.400 IPM extensions discarded + Discarded-X400-MTS-Extensions + Mail X.400 MTS extensions discarded + Disclose-Recipients Mail Disclose names of other + recipients? + Deferred-Delivery Mail Deferred delivery information + Latest-Delivery-Time + Mail Latest delivery time requested + Originator-Return-Address + Mail Originator return address + X400-Content-Identifier + Mail Message content identifier + X400-Content-Return Mail Return content on non-delivery? + X400-Content-Type Mail X400 content type + X400-MTS-Identifier Mail X400 MTS-Identifier + X400-Originator Mail X400 Originator + X400-Received Mail X400 Received + X400-Recipients Mail X400 Recipients + X400-Trace Mail X400 Trace + +2.1.1. Header Field: Date + + Description: + Message date and time + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.1) + + Related information: + Specifies the date and time at which the creator of the message + indicated that the message was complete and ready to enter the + mail delivery system. Defined as standard by RFC 822. + + + + + +G. Klyne, et al. Standards Track [Page 6] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.2. Header Field: From + + Description: + Mailbox of message author + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.2) + + Related information: + Specifies the author(s) of the message; that is, the mailbox(es) + of the person(s) or system(s) responsible for the writing of the + message. Defined as standard by RFC 822. + +2.1.3. Header Field: Sender + + Description: + Mailbox of message sender + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.2) + + Related information: + Specifies the mailbox of the agent responsible for the actual + transmission of the message. Defined as standard by RFC 822. + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 7] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.4. Header Field: Reply-To + + Description: + Mailbox for replies to message + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.2) + + Related information: + When the "Reply-To:" field is present, it indicates the + mailbox(es) to which the author of the message suggests that + replies be sent. Defined as standard by RFC 822. + +2.1.5. Header Field: To + + Description: + Primary recipient mailbox + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.3) + + Related information: + Contains the address(es) of the primary recipient(s) of the + message. Defined as standard by RFC 822. + + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 8] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.6. Header Field: Cc + + Description: + Carbon-copy recipient mailbox + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.3) + + Related information: + Contains the addresses of others who are to receive the message, + though the content of the message may not be directed at them. + Defined as standard by RFC 822. + +2.1.7. Header Field: Bcc + + Description: + Blind-carbon-copy recipient mailbox + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.3) + + Related information: + Contains addresses of recipients of the message whose addresses + are not to be revealed to other recipients of the message. + Defined as standard by RFC 822. + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 9] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.8. Header Field: Message-ID + + Description: + Message identifier + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.4) + + Related information: + Contains a single unique message identifier that refers to a + particular version of a particular message. If the message is + resent without changes, the original Message-ID is retained. + Defined as standard by RFC 822. + +2.1.9. Header Field: In-Reply-To + + Description: + Identify replied-to message(s) + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.4) + + Related information: + The message identifier(s) of the original message(s) to which the + current message is a reply. Defined as standard by RFC 822. + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 10] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.10. Header Field: References + + Description: + Related message identifier(s) + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.4) + + Related information: + The message identifier(s) of other message(s) to which the current + message may be related. In RFC 2822, the definition was changed + to say that this header field contains a list of all Message-IDs + of messages in the preceding reply chain. Defined as standard by + RFC 822. + +2.1.11. Header Field: Subject + + Description: + Topic of message + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.5) + + Related information: + Contains a short string identifying the topic of the message. + Defined as standard by RFC 822. + + + + + + + + + +G. Klyne, et al. Standards Track [Page 11] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.12. Header Field: Comments + + Description: + Additional comments about the message + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.5) + + Related information: + Contains any additional comments on the text of the body of the + message. Warning: Some mailers will not show this field to + recipients. Defined as standard by RFC 822. + +2.1.13. Header Field: Keywords + + Description: + Message key words and/or phrases + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.5) + + Related information: + Contains a comma-separated list of important words and phrases + that might be useful for the recipient. Defined as standard by + RFC 822. + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 12] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.14. Header Field: Resent-Date + + Description: + Date and time message is resent + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.6) + + Related information: + Contains the date and time that a message is reintroduced into the + message transfer system. Defined as standard by RFC 822. + +2.1.15. Header Field: Resent-From + + Description: + Mailbox of person for whom message is resent + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.6) + + Related information: + Contains the mailbox of the agent who has reintroduced the message + into the message transfer system, or on whose behalf the message + has been resent. Defined as standard by RFC 822. + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 13] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.16. Header Field: Resent-Sender + + Description: + Mailbox of person who actually resends the message + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.6) + + Related information: + Contains the mailbox of the agent who has reintroduced the message + into the message transfer system, if this is different from the + Resent-From value. Defined as standard by RFC 822. + +2.1.17. Header Field: Resent-To + + Description: + Mailbox to which message is resent + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.6) + + Related information: + Contains the mailbox(es) to which the message has been resent. + Defined as standard by RFC 822. + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 14] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.18. Header Field: Resent-Cc + + Description: + Mailbox(es) to which message is cc'ed on resend + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.6) + + Related information: + Contains the mailbox(es) to which message is cc'ed on resend. + Defined as standard by RFC 822. + +2.1.19. Header Field: Resent-Bcc + + Description: + Mailbox(es) to which message is bcc'ed on resend + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.6) + + Related information: + Contains the mailbox(es) to which message is bcc'ed on resend. + Defined as standard by RFC 822. + + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 15] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.20. Header Field: Resent-Reply-To + + Description: + Resent reply-to + + Applicable protocol: Mail [18] + + Status: obsolete + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] + + Related information: + Resent Reply-to. Defined by RFC 822, obsoleted by RFC 2822. + +2.1.21. Header Field: Resent-Message-ID + + Description: + Message identifier for resent message + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.6) + + Related information: + Contains a message identifier for a resent message. Defined as + standard by RFC 822. + + + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 16] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.22. Header Field: Return-Path + + Description: + Message return path + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.7) + + Related information: + Return path for message response diagnostics. See also RFC 2821 + [17]. Defined as standard by RFC 822. + +2.1.23. Header Field: Received + + Description: + Mail transfer trace information + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2822 [18] (section 3.6.7) + + Related information: + Contains information about receipt of the current message by a + mail transfer agent on the transfer path. See also RFC 2821 [17]. + Defined as standard by RFC 822. + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 17] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.24. Header Field: Encrypted + + Description: + Message encryption information + + Applicable protocol: Mail [18] + + Status: obsolete + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 822 [2] + + Related information: + Defined by RFC 822, but was found to be inadequately specified, + was not widely implemented, and was removed in RFC 2822. Current + practice is to use separate encryption, such as S/MIME or OpenPGP, + possibly in conjunction with RFC 1847 MIME security multiparts. + +2.1.25. Header Field: Disposition-Notification-To + + Description: + Mailbox for sending disposition notification + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2298 [12] + + Related information: + Indicates that the sender wants a disposition notification when + this message is received (read, processed, etc.) by its + recipients. + + + + + + + + + +G. Klyne, et al. Standards Track [Page 18] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.26. Header Field: Disposition-Notification-Options + + Description: + Disposition notification options + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2298 [12] + + Related information: + For optional modifiers on disposition notification requests. + +2.1.27. Header Field: Accept-Language + + Description: + Language(s) for auto-responses + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 3282 [21] + + Related information: + Indicates a language that the message sender requests to be used + for responses. Accept-language was not designed for email but has + been considered useful as input to the generation of automatic + replies. Some problems have been noted concerning its use with + email, including but not limited to determination of the email + address to which it refers; cost and lack of effective + internationalization of email responses; interpretation of + language subtags; and determining what character set encoding + should be used. + + + + + + +G. Klyne, et al. Standards Track [Page 19] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.28. Header Field: Original-Message-ID + + Description: + Original message identifier + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 3297 [22] + + Related information: + Original message identifier used with resend of message with + alternative content format; identifies the original message data + to which it corresponds. + +2.1.29. Header Field: PICS-Label + + Description: + PICS rating label + + Applicable protocol: Mail [18] + + Status: standard + + Author/change controller: + W3C (mailto:web-human@w3.org) + World Wide Web Consortium + + Specification document(s): + PICS-labels [24] + + Related information: + Ratings label to control selection (filtering) of messages + according to the PICS protocol. Specified for general use with + RFC 822 message format, with HTTP-specific extensions. + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 20] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.30. Header Field: Encoding + + Description: + Message encoding and other information + + Applicable protocol: Mail [18] + + Status: experimental + + Author/change controller: + Albert K. Costanzo (mailto:AL@AKC.COM) + AKC Consulting Inc. + + Specification document(s): + RFC 1505 [4] + + Related information: + Used in several different ways by different mail systems. Some + use it for a kind of content-type information, some for encoding + and length information, some for a kind of boundary information, + and some in other ways. + +2.1.31. Header Field: List-Archive + + Description: + URL of mailing list archive + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2369 [13] + + Related information: + Contains the URL to use to browse the archives of the mailing list + from which this message was relayed. + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 21] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.32. Header Field: List-Help + + Description: + URL for mailing list information + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2369 [13] + + Related information: + Contains the URL to use to get information about the mailing list + from which this message was relayed. + +2.1.33. Header Field: List-ID + + Description: + Mailing list identifier + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2919 [20] + + Related information: + Stores an identification of the mailing list through which this + message was distributed. + + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 22] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.34. Header Field: List-Owner + + Description: + URL for mailing list owner's mailbox + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2369 [13] + + Related information: + Contains the URL to send e-mail to the owner of the mailing list + from which this message was relayed. + +2.1.35. Header Field: List-Post + + Description: + URL for mailing list posting + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2369 [13] + + Related information: + Contains the URL to use to send contributions to the mailing list + from which this message was relayed. + + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 23] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.36. Header Field: List-Subscribe + + Description: + URL for mailing list subscription + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2369 [13] + + Related information: + Contains the URL to use to get a subscription to the mailing list + from which this message was relayed. + +2.1.37. Header Field: List-Unsubscribe + + Description: + URL for mailing list unsubscription + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2369 [13] + + Related information: + Contains the URL to use to unsubscribe the mailing list from which + this message was relayed. + + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 24] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.38. Header Field: Message-Context + + Description: + Type or context of message + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 3458 [23] + + Related information: + Provides information about the context and presentation + characteristics of a message. Can have the values 'voice- + message', 'fax-message', 'pager-message', 'multimedia-message', + 'text-message', or 'none'. + +2.1.39. Header Field: DL-Expansion-History + + Description: + Trace of distribution lists passed + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Trace of distribution lists passed. (MIXER X.400 mapping; not for + general use.) + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 25] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.40. Header Field: Alternate-Recipient + + Description: + Controls forwarding to alternate recipients + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Controls whether this message may be forwarded to an alternate + recipient, such as a postmaster, if delivery to the intended + recipient is not possible. Default: Allowed. RFC 2156 (MIXER), + not for general use. + +2.1.41. Header Field: Original-Encoded-Information-Types + + Description: + Body part types in message + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Which body part types occur in this message. RFC 2156 (MIXER); + not for general use. + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 26] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.42. Header Field: Content-Return + + Description: + Return content on non-delivery? + + Applicable protocol: Mail [18] + + Status: obsolete + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 1327 [3] + + Related information: + Indicates whether the content of a message is to be returned with + non-delivery notifications. Introduced by RFC 1327 and + subsequently changed by RFC 2156 to avoid confusion with MIME + defined fields. + +2.1.43. Header Field: Generate-Delivery-Report + + Description: + Request delivery report generation + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Indicates whether a delivery report is wanted at successful + delivery. Default is not to generate such a report. RFC 2156 + (MIXER); not for general use. + + + + + + + + + +G. Klyne, et al. Standards Track [Page 27] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.44. Header Field: Prevent-NonDelivery-Report + + Description: + Non-delivery report required? + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Indicates whether a non-delivery report is wanted on delivery + error. Default is to generate such a report. RFC 2156 (MIXER); + not for general use. + +2.1.45. Header Field: Obsoletes + + Description: + Reference message to be replaced + + Applicable protocol: Mail [18] + + Status: obsolete + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 1327 [3] + + Related information: + Reference to a previous message being corrected and replaced. + Compare to 'Supersedes:',f used in Usenet News. Introduced by RFC + 1327 and subsequently renamed by RFC 2156 to 'Supersedes'. + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 28] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.46. Header Field: Supersedes + + Description: + Reference message to be replaced + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Reference to a previous message being corrected and replaced. + Renamed version of obsolete 'Obsoletes' header field. RFC 2156 + (MIXER); not for general use. + +2.1.47. Header Field: Content-Identifier + + Description: + Message content identifier + + Applicable protocol: Mail [18] + + Status: obsolete + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 1327 [3] + + Related information: + A text string that identifies the content of a message. + Introduced by RFC 1327 and subsequently changed by RFC 2156 to + avoid confusion with MIME defined fields. Gateways that reverse + map may support the old field. + + + + + + + + + +G. Klyne, et al. Standards Track [Page 29] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.48. Header Field: Delivery-Date + + Description: + Message delivery time + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + The time when a message was delivered to its recipient. RFC 2156 + (MIXER); not for general use. + +2.1.49. Header Field: Expiry-Date + + Description: + Message expiry time + + Applicable protocol: Mail [18] + + Status: obsolete + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 1327 [3] + + Related information: + Time at which a message loses its validity. Introduced by RFC + 1327 and subsequently changed by RFC 2156 to 'Expires:'. + + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 30] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.50. Header Field: Expires + + Description: + Message expiry time + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Time at which a message loses its validity. Renamed version of + obsolete Expiry-Date header field. RFC 2156 (MIXER), not for + general use. + +2.1.51. Header Field: Reply-By + + Description: + Time by which a reply is requested + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Latest time by which a reply is requested (not demanded). RFC + 2156 (MIXER); not for general use. + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 31] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.52. Header Field: Importance + + Description: + Message importance + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + A hint from the originator to the recipients about how important a + message is. Values: High, normal, or low. Not used to control + transmission speed. Proposed for use with RFC 2156 (MIXER) [10] + and RFC 3801 (VPIM) [14]. + +2.1.53. Header Field: Incomplete-Copy + + Description: + Body parts are missing + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Body parts are missing. RFC 2156 (MIXER); not for general use. + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 32] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.54. Header Field: Priority + + Description: + Message priority + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Can be 'normal', 'urgent', or 'non-urgent' and can influence + transmission speed and delivery. RFC 2156 (MIXER); not for + general use. + +2.1.55. Header Field: Sensitivity + + Description: + Message content sensitivity + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + How sensitive it is to disclose this message to people other than + the specified recipients. Values: Personal, private, and company + confidential. The absence of this header field in messages + gatewayed from X.400 indicates that the message is not sensitive. + Proposed for use with RFC 2156 (MIXER) [10] and RFC 3801 (VPIM) + [14]. + + + + + + + +G. Klyne, et al. Standards Track [Page 33] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.56. Header Field: Language + + Description: + X.400 message content language + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Can include a code for the natural language used in a message; + e.g., 'en' for English. See also 'Content-Language'. RFC 2156 + (MIXER); not for general use. + +2.1.57. Header Field: Conversion + + Description: + Conversion allowed? + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + The body of this message may not be converted from one character + set to another. Values: prohibited and allowed. RFC 2156 + (MIXER); not for general use. + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 34] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.58. Header Field: Conversion-With-Loss + + Description: + Lossy conversion allowed? + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + The body of this message may not be converted from one character + set to another if information will be lost. Values: prohibited + and allowed. RFC 2156 (MIXER); not for general use. + +2.1.59. Header Field: Message-Type + + Description: + Message type: delivery report? + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Only used with the value 'Delivery Report' to indicate that this + is a delivery report gatewayed from X.400. RFC 2156 (MIXER); not + for general use. + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 35] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.60. Header Field: Autosubmitted + + Description: + Automatically submitted indicator + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Has been automatically submitted. RFC 2156 (MIXER); not for + general use. + +2.1.61. Header Field: Autoforwarded + + Description: + Automatically forwarded indicator + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Has been automatically forwarded. RFC 2156 (MIXER), not for + general use. + + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 36] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.62. Header Field: Discarded-X400-IPMS-Extensions + + Description: + X.400 IPM extensions discarded + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Can be used in Internet mail to indicate X.400 IPM extensions that + could not be mapped to Internet mail format. RFC 2156 (MIXER); + not for general use. + +2.1.63. Header Field: Discarded-X400-MTS-Extensions + + Description: + X.400 MTS extensions discarded + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Can be used in Internet mail to indicate X.400 MTS extensions that + could not be mapped to Internet mail format. RFC 2156 (MIXER); + not for general use. + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 37] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.64. Header Field: Disclose-Recipients + + Description: + Disclose names of other recipients? + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Tells whether recipients are to be told the names of other + recipients of the same message. This is primarily an X.400 + facility. In X.400, this is an envelope attribute and refers to + disclosure of the envelope recipient list. Disclosure of other + recipients is done in Internet mail via the To:, cc:, and bcc: + header fields. Not for general use. + +2.1.65. Header Field: Deferred-Delivery + + Description: + Deferred delivery information + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Provides information about deferred delivery service to the + recipient. RFC 2156 (MIXER); not for general use. + + + + + + + + +G. Klyne, et al. Standards Track [Page 38] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.66. Header Field: Latest-Delivery-Time + + Description: + Latest delivery time requested + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Provides the recipient with information about requested delivery + but will not be acted on by the SMTP infrastructure. RFC 2156 + (MIXER); not for general use. + +2.1.67. Header Field: Originator-Return-Address + + Description: + Originator return address + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Originator return address. RFC 2156 (MIXER); not for general use. + + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 39] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.68. Header Field: X400-Content-Identifier + + Description: + Message content identifier + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + A text string that identifies the content of a message. Renamed + version of obsolete Content-Identifier field. RFC 2156 (MIXER); + not for general use. + +2.1.69. Header Field: X400-Content-Return + + Description: + Return content on non-delivery? + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + Indicates whether the content of a message is to be returned with + non-delivery notifications. Renamed version of obsolete Content- + Return field. RFC 2156 (MIXER); not for general use. + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 40] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.70. Header Field: X400-Content-Type + + Description: + X400 content type + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + X400 content type. RFC 2156 (MIXER); not for general use. + +2.1.71. Header Field: X400-MTS-Identifier + + Description: + X400 MTS-Identifier + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + X400 MTS-Identifier. RFC 2156 (MIXER); not for general use. + + + + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 41] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.72. Header Field: X400-Originator + + Description: + X400 Originator + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + X400 Originator. RFC 2156 (MIXER); not for general use. + +2.1.73. Header Field: X400-Received + + Description: + X400 Received + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + X400 Received. RFC 2156 (MIXER); not for general use. + + + + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 42] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.1.74. Header Field: X400-Recipients + + Description: + X400 Recipients + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + X400 Recipients. RFC 2156 (MIXER); not for general use. + +2.1.75. Header Field: X400-Trace + + Description: + X400 Trace + + Applicable protocol: Mail [18] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2156 [10] + + Related information: + X400 Trace. RFC 2156 (MIXER), not for general use. + + + + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 43] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.2. Permanent MIME Header Field Registrations + + Header name Protocol + ----------- -------- + MIME-Version MIME MIME version number + Content-ID MIME Identify content body part + Content-Description MIME Description of message body part + Content-Transfer-Encoding + MIME Content transfer encoding applied + Content-Type MIME MIME content type + Content-Base MIME Base to be used for resolving + relative URIs within this content + part + Content-Location MIME URI for retrieving a body part + Content-features MIME Indicates content features of a + MIME body part + Content-Disposition MIME Intended content disposition and + file name + Content-Language MIME Language of message content + Content-Alternative MIME Alternative content available + Content-MD5 MIME MD5 checksum of content + Content-Duration MIME Time duration of content + +2.2.1. Header Field: MIME-Version + + Description: + MIME version number + + Applicable protocol: MIME [7] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2045 [7] (section 4) + + Related information: + An indicator that this message is formatted according to the MIME + standard, and an indication of which version of MIME is used. + + + + + + + + + +G. Klyne, et al. Standards Track [Page 44] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.2.2. Header Field: Content-ID + + Description: + Identify content body part + + Applicable protocol: MIME [7] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2045 [7] (section 7) + + Related information: + Specifies a Unique ID for one MIME body part of the content of a + message. + +2.2.3. Header Field: Content-Description + + Description: + Description of message body part + + Applicable protocol: MIME [7] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2045 [7] (section 8) + + Related information: + Description of a particular body part of a message; for example, a + caption for an image body part. + + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 45] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.2.4. Header Field: Content-Transfer-Encoding + + Description: + Content transfer encoding applied + + Applicable protocol: MIME [7] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2045 [7] (section 6) + + Related information: + Coding method used in a MIME message body part. + +2.2.5. Header Field: Content-Type + + Description: + MIME content type + + Applicable protocol: MIME [7] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2045 [7] (section 5) + + Related information: + Format of content (character set, etc.) Note that the values for + this header field are defined in different ways in RFC 1049 and in + MIME (RFC 2045). The 'MIME-version' header field will show + whether Content-Type is to be interpreted according to RFC 1049 or + according to MIME. The MIME definition should be used in + generating mail. RFC 1049 has 'historic' status. RFC 1766 [5] + defines a parameter 'difference' to this header field. Various + other Content-Type define various additional parameters. For + example, the parameter 'charset' is mandatory for all textual + Content-Types. See also RFC 1049, RFC 1123: 5.2.13, and RFC 1766: + 4.1. + + + + +G. Klyne, et al. Standards Track [Page 46] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.2.6. Header Field: Content-Base + + Description: + Base to be used for resolving relative URIs within this content + part. + + Applicable protocol: MIME [7] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2110 [8] + + Related information: + Base to be used for resolving relative URIs within this content + part. See also Content-Location. This header was included in the + first version of MHTML and HTTP 1.1 but removed in the second + version (RFC 2557). + +2.2.7. Header Field: Content-Location + + Description: + URI for retrieving a body part + + Applicable protocol: MIME [7] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2557 [16] + + Related information: + URI using which the content of this body-part part was retrieved, + might be retrievable, or which otherwise gives a globally unique + identification of the content. + + + + + + + + +G. Klyne, et al. Standards Track [Page 47] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.2.8. Header Field: Content-features + + Description: + Indicates content features of a MIME body part + + Applicable protocol: MIME [7] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2912 [19] (section 3) + + Related information: + The 'Content-features:' header can be used to annotate a MIME body + part with a media feature expression, to indicate features of the + body part content. See also RFC 2533, RFC 2506, and RFC 2045. + +2.2.9. Header Field: Content-Disposition + + Description: + Intended content disposition and file name + + Applicable protocol: MIME [7] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2183 [11] + + Related information: + Indicates whether a MIME body part is to be shown inline or is an + attachment; can also indicate a suggested filename for use when + saving an attachment to a file. + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 48] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.2.10. Header Field: Content-Language + + Description: + Language of message content + + Applicable protocol: MIME [7] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 3282 [21] + + Related information: + Can include a code for the natural language used in a message; + e.g., 'en' for English. Can also contain a list of languages for + a message containing more than one language. + +2.2.11. Header Field: Content-Alternative + + Description: + Alternative content available + + Applicable protocol: MIME [7] + + Status: work-in-progress + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 3297 [22] + + Related information: + Information about the media features of alternative content + formats available for the current message. + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 49] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +2.2.12. Header Field: Content-MD5 + + Description: + MD5 checksum of content + + Applicable protocol: MIME [7] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 1864 [6] + + Related information: + Checksum of content to ensure that it has not been modified. + +2.2.13. Header Field: Content-Duration + + Description: + Time duration of content + + Applicable protocol: MIME [7] + + Status: standards-track + + Author/change controller: + IETF (mailto:iesg@ietf.org) + Internet Engineering Task Force + + Specification document(s): + RFC 2424 [15] + + Related information: + Time duration of body part content, in seconds (e.g., for audio + message). + +3. IANA Considerations + + Section 2 of this specification provides initial registrations of + mail and MIME header fields in the "Permanent Message Header Field + Registry", defined by registration procedures for message header + fields [1]. + + + + + + +G. Klyne, et al. Standards Track [Page 50] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +4. Security Considerations + + No security considerations are introduced by this registration + document beyond those already inherent in use of the mail message + header fields referenced. + +5. Acknowledgements + + Most of the information in this document has been derived from Jacob + Palme's work in RFC 2076 [25] and subsequent updates [26]. The + authors also gratefully acknowledge contributions and constructive + input from Mark Nottingham, Bruce Lilly, Keith Moore, and Charles + Lindsey (the mention of whom is not intended to imply their + unqualified support for material herein). + +6. References + +6.1. Normative References + + [1] Klyne, G., Nottingham, M., and J. Mogul, "Registration + Procedures for Message Header Fields", BCP 90, RFC 3864, + September 2004. + + [2] Crocker, D., "Standard for the format of ARPA Internet text + messages", STD 11, RFC 822, August 1982. + + [3] Hardcastle-Kille, S., "Mapping between X.400(1988) / ISO 10021 + and RFC 822", RFC 1327, May 1992. + + [4] Costanzo, A., Robinson, D., and R. Ullmann, "Encoding Header + Field for Internet Messages", RFC 1505, August 1993. + + [5] Alvestrand, H., "Tags for the Identification of Languages", RFC + 1766, March 1995. + + [6] Myers, J. and M. Rose, "The Content-MD5 Header Field", RFC 1864, + October 1995. + + [7] Freed, N. and N. Borenstein, "Multipurpose Internet Mail + Extensions (MIME) Part One: Format of Internet Message Bodies", + RFC 2045, November 1996. + + [8] Palme, J. and A. Hopmann, "MIME E-mail Encapsulation of + Aggregate Documents, such as HTML (MHTML)", RFC 2110, March + 1997. + + [9] Bradner, S., "Key words for use in RFCs to Indicate Requirement + Levels", BCP 14, RFC 2119, March 1997. + + + +G. Klyne, et al. Standards Track [Page 51] + +RFC 4021 Mail and MIME Header Fields March 2005 + + + [10] Kille, S., "MIXER (Mime Internet X.400 Enhanced Relay): Mapping + between X.400 and RFC 822/MIME", RFC 2156, January 1998. + + [11] Troost, R., Dorner, S., and K. Moore, "Communicating + Presentation Information in Internet Messages: The Content- + Disposition Header Field", RFC 2183, August 1997. + + [12] Hansen, T. and G. Vaudreuil, "Message Disposition Notification", + RFC 3798, May 2004. + + [13] Neufeld, G. and J. Baer, "The Use of URLs as Meta-Syntax for + Core Mail List Commands and their Transport through Message + Header Fields", RFC 2369, July 1998. + + [14] Vaudreuil, G. and G. Parsons, "Voice Profile for Internet Mail - + version 2 (VPIMv2)", RFC 3801, June 2004. + + [15] Vaudreuil, G. and G. Parsons, "Content Duration MIME Header + Definition", RFC 3803, June 2004. + + [16] Palme, J., Hopmann, A., and N. Shelness, "MIME Encapsulation of + Aggregate Documents, such as HTML (MHTML)", RFC 2557, March + 1999. + + [17] Klensin, J., "Simple Mail Transfer Protocol", RFC 2821, April + 2001. + + [18] Resnick, P., "Internet Message Format", RFC 2822, April 2001. + + [19] Klyne, G., "Indicating Media Features for MIME Content", RFC + 2912, September 2000. + + [20] Chandhok, R. and G. Wenger, "List-Id: A Structured Field and + Namespace for the Identification of Mailing Lists", RFC 2919, + March 2001. + + [21] Alvestrand, H., "Content Language Headers", RFC 3282, May 2002. + + [22] Klyne, G., Iwazaki, R., and D. Crocker, "Content Negotiation for + Messaging Services based on Email", RFC 3297, July 2002. + + [23] Burger, E., Candell, E., Eliot, C., and G. Klyne, "Message + Context for Internet Mail", RFC 3458, January 2003. + + [24] Miller, J., Krauskopf, T., Resnick, P. and W. Treese, "PICS + Label Distribution Label Syntax and Communication Protocols", + W3C Recommendation REC-PICS-labels, October 1996, + <http://www.w3.org/TR/REC-PICS-labels>. + + + +G. Klyne, et al. Standards Track [Page 52] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +6.2. Informative References + + [25] Palme, J., "Common Internet Message Headers", RFC 2076, February + 1997. + + [26] Palme, J., "Common Internet Message Header Fields", Work in + Progress. + +URIs + + [27] <http://www.ninebynine.org/IETF/Messaging/HdrRegistry/ + Intro.html> + +Authors' Addresses + + Graham Klyne + Image Bioinformatics Research Group + Department of Zoology, University of Oxford + South Parks Road, Oxford OX1 3PS, UK + + Phone: +44-(0)1865-281991 + Fax: +44-(0)1865-310447 + EMail: GK-IETF@ninebynine.org + + + Jacob Palme + Stockholm University/KTH + Forum 100 + Kista S-164 40 + Sweden + + Phone: +46-8-16 16 67 + Fax: +46-8-783 08 29 + EMail: jpalme@dsv.su.se + + + + + + + + + + + + + + + + + +G. Klyne, et al. Standards Track [Page 53] + +RFC 4021 Mail and MIME Header Fields March 2005 + + +Full Copyright Statement + + Copyright (C) The Internet Society (2005). + + This document is subject to the rights, licenses and restrictions + contained in BCP 78, and except as set forth therein, the authors + retain all their rights. + + This document and the information contained herein are provided on an + "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS + OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET + ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, + INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE + INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED + WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. + +Intellectual Property + + The IETF takes no position regarding the validity or scope of any + Intellectual Property Rights or other rights that might be claimed to + pertain to the implementation or use of the technology described in + this document or the extent to which any license under such rights + might or might not be available; nor does it represent that it has + made any independent effort to identify any such rights. Information + on the procedures with respect to rights in RFC documents can be + found in BCP 78 and BCP 79. + + Copies of IPR disclosures made to the IETF Secretariat and any + assurances of licenses to be made available, or the result of an + attempt made to obtain a general license or permission for the use of + such proprietary rights by implementers or users of this + specification can be obtained from the IETF on-line IPR repository at + http://www.ietf.org/ipr. + + The IETF invites any interested party to bring to its attention any + copyrights, patents or patent applications, or other proprietary + rights that may cover technology that may be required to implement + this standard. Please address the information to the IETF at ietf- + ipr@ietf.org. + +Acknowledgement + + Funding for the RFC Editor function is currently provided by the + Internet Society. + + + + + + + +G. Klyne, et al. Standards Track [Page 54] + |