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+Network Working Group                                 P. Resnick, Editor
+Request for Comments: 2822                         QUALCOMM Incorporated
+Obsoletes: 822                                                April 2001
+Category: Standards Track
+
+
+                        Internet Message Format
+
+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 (2001).  All Rights Reserved.
+
+Abstract
+
+   This standard specifies a syntax for text messages that are sent
+   between computer users, within the framework of "electronic mail"
+   messages.  This standard supersedes the one specified in Request For
+   Comments (RFC) 822, "Standard for the Format of ARPA Internet Text
+   Messages", updating it to reflect current practice and incorporating
+   incremental changes that were specified in other RFCs.
+
+Table of Contents
+
+   1. Introduction ............................................... 3
+   1.1. Scope .................................................... 3
+   1.2. Notational conventions ................................... 4
+   1.2.1. Requirements notation .................................. 4
+   1.2.2. Syntactic notation ..................................... 4
+   1.3. Structure of this document ............................... 4
+   2. Lexical Analysis of Messages ............................... 5
+   2.1. General Description ...................................... 5
+   2.1.1. Line Length Limits ..................................... 6
+   2.2. Header Fields ............................................ 7
+   2.2.1. Unstructured Header Field Bodies ....................... 7
+   2.2.2. Structured Header Field Bodies ......................... 7
+   2.2.3. Long Header Fields ..................................... 7
+   2.3. Body ..................................................... 8
+   3. Syntax ..................................................... 9
+   3.1. Introduction ............................................. 9
+   3.2. Lexical Tokens ........................................... 9
+
+
+
+Resnick                     Standards Track                     [Page 1]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   3.2.1. Primitive Tokens ....................................... 9
+   3.2.2. Quoted characters ......................................10
+   3.2.3. Folding white space and comments .......................11
+   3.2.4. Atom ...................................................12
+   3.2.5. Quoted strings .........................................13
+   3.2.6. Miscellaneous tokens ...................................13
+   3.3. Date and Time Specification ..............................14
+   3.4. Address Specification ....................................15
+   3.4.1. Addr-spec specification ................................16
+   3.5 Overall message syntax ....................................17
+   3.6. Field definitions ........................................18
+   3.6.1. The origination date field .............................20
+   3.6.2. Originator fields ......................................21
+   3.6.3. Destination address fields .............................22
+   3.6.4. Identification fields ..................................23
+   3.6.5. Informational fields ...................................26
+   3.6.6. Resent fields ..........................................26
+   3.6.7. Trace fields ...........................................28
+   3.6.8. Optional fields ........................................29
+   4. Obsolete Syntax ............................................29
+   4.1. Miscellaneous obsolete tokens ............................30
+   4.2. Obsolete folding white space .............................31
+   4.3. Obsolete Date and Time ...................................31
+   4.4. Obsolete Addressing ......................................33
+   4.5. Obsolete header fields ...................................33
+   4.5.1. Obsolete origination date field ........................34
+   4.5.2. Obsolete originator fields .............................34
+   4.5.3. Obsolete destination address fields ....................34
+   4.5.4. Obsolete identification fields .........................35
+   4.5.5. Obsolete informational fields ..........................35
+   4.5.6. Obsolete resent fields .................................35
+   4.5.7. Obsolete trace fields ..................................36
+   4.5.8. Obsolete optional fields ...............................36
+   5. Security Considerations ....................................36
+   6. Bibliography ...............................................37
+   7. Editor's Address ...........................................38
+   8. Acknowledgements ...........................................39
+   Appendix A. Example messages ..................................41
+   A.1. Addressing examples ......................................41
+   A.1.1. A message from one person to another with simple
+          addressing .............................................41
+   A.1.2. Different types of mailboxes ...........................42
+   A.1.3. Group addresses ........................................43
+   A.2. Reply messages ...........................................43
+   A.3. Resent messages ..........................................44
+   A.4. Messages with trace fields ...............................46
+   A.5. White space, comments, and other oddities ................47
+   A.6. Obsoleted forms ..........................................47
+
+
+
+Resnick                     Standards Track                     [Page 2]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   A.6.1. Obsolete addressing ....................................48
+   A.6.2. Obsolete dates .........................................48
+   A.6.3. Obsolete white space and comments ......................48
+   Appendix B. Differences from earlier standards ................49
+   Appendix C. Notices ...........................................50
+   Full Copyright Statement ......................................51
+
+1. Introduction
+
+1.1. Scope
+
+   This standard specifies a syntax for text messages that are sent
+   between computer users, within the framework of "electronic mail"
+   messages.  This standard supersedes the one specified in Request For
+   Comments (RFC) 822, "Standard for the Format of ARPA Internet Text
+   Messages" [RFC822], updating it to reflect current practice and
+   incorporating incremental changes that were specified in other RFCs
+   [STD3].
+
+   This standard specifies a syntax only for text messages.  In
+   particular, it makes no provision for the transmission of images,
+   audio, or other sorts of structured data in electronic mail messages.
+   There are several extensions published, such as the MIME document
+   series [RFC2045, RFC2046, RFC2049], which describe mechanisms for the
+   transmission of such data through electronic mail, either by
+   extending the syntax provided here or by structuring such messages to
+   conform to this syntax.  Those mechanisms are outside of the scope of
+   this standard.
+
+   In the context of electronic mail, messages are viewed as having an
+   envelope and contents.  The envelope contains whatever information is
+   needed to accomplish transmission and delivery.  (See [RFC2821] for a
+   discussion of the envelope.)  The contents comprise the object to be
+   delivered to the recipient.  This standard applies only to the format
+   and some of the semantics of message contents.  It contains no
+   specification of the information in the envelope.
+
+   However, some message systems may use information from the contents
+   to create the envelope.  It is intended that this standard facilitate
+   the acquisition of such information by programs.
+
+   This specification is intended as a definition of what message
+   content format is to be passed between systems.  Though some message
+   systems locally store messages in this format (which eliminates the
+   need for translation between formats) and others use formats that
+   differ from the one specified in this standard, local storage is
+   outside of the scope of this standard.
+
+
+
+
+Resnick                     Standards Track                     [Page 3]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   Note: This standard is not intended to dictate the internal formats
+   used by sites, the specific message system features that they are
+   expected to support, or any of the characteristics of user interface
+   programs that create or read messages.  In addition, this standard
+   does not specify an encoding of the characters for either transport
+   or storage; that is, it does not specify the number of bits used or
+   how those bits are specifically transferred over the wire or stored
+   on disk.
+
+1.2. Notational conventions
+
+1.2.1. Requirements notation
+
+   This document occasionally uses terms that appear in capital letters.
+   When the terms "MUST", "SHOULD", "RECOMMENDED", "MUST NOT", "SHOULD
+   NOT", and "MAY" appear capitalized, they are being used to indicate
+   particular requirements of this specification.  A discussion of the
+   meanings of these terms appears in [RFC2119].
+
+1.2.2. Syntactic notation
+
+   This standard uses the Augmented Backus-Naur Form (ABNF) notation
+   specified in [RFC2234] for the formal definitions of the syntax of
+   messages.  Characters will be specified either by a decimal value
+   (e.g., the value %d65 for uppercase A and %d97 for lowercase A) or by
+   a case-insensitive literal value enclosed in quotation marks (e.g.,
+   "A" for either uppercase or lowercase A).  See [RFC2234] for the full
+   description of the notation.
+
+1.3. Structure of this document
+
+   This document is divided into several sections.
+
+   This section, section 1, is a short introduction to the document.
+
+   Section 2 lays out the general description of a message and its
+   constituent parts.  This is an overview to help the reader understand
+   some of the general principles used in the later portions of this
+   document.  Any examples in this section MUST NOT be taken as
+   specification of the formal syntax of any part of a message.
+
+   Section 3 specifies formal ABNF rules for the structure of each part
+   of a message (the syntax) and describes the relationship between
+   those parts and their meaning in the context of a message (the
+   semantics).  That is, it describes the actual rules for the structure
+   of each part of a message (the syntax) as well as a description of
+   the parts and instructions on how they ought to be interpreted (the
+   semantics).  This includes analysis of the syntax and semantics of
+
+
+
+Resnick                     Standards Track                     [Page 4]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   subparts of messages that have specific structure.  The syntax
+   included in section 3 represents messages as they MUST be created.
+   There are also notes in section 3 to indicate if any of the options
+   specified in the syntax SHOULD be used over any of the others.
+
+   Both sections 2 and 3 describe messages that are legal to generate
+   for purposes of this standard.
+
+   Section 4 of this document specifies an "obsolete" syntax.  There are
+   references in section 3 to these obsolete syntactic elements.  The
+   rules of the obsolete syntax are elements that have appeared in
+   earlier revisions of this standard or have previously been widely
+   used in Internet messages.  As such, these elements MUST be
+   interpreted by parsers of messages in order to be conformant to this
+   standard.  However, since items in this syntax have been determined
+   to be non-interoperable or to cause significant problems for
+   recipients of messages, they MUST NOT be generated by creators of
+   conformant messages.
+
+   Section 5 details security considerations to take into account when
+   implementing this standard.
+
+   Section 6 is a bibliography of references in this document.
+
+   Section 7 contains the editor's address.
+
+   Section 8 contains acknowledgements.
+
+   Appendix A lists examples of different sorts of messages.  These
+   examples are not exhaustive of the types of messages that appear on
+   the Internet, but give a broad overview of certain syntactic forms.
+
+   Appendix B lists the differences between this standard and earlier
+   standards for Internet messages.
+
+   Appendix C has copyright and intellectual property notices.
+
+2. Lexical Analysis of Messages
+
+2.1. General Description
+
+   At the most basic level, a message is a series of characters.  A
+   message that is conformant with this standard is comprised of
+   characters with values in the range 1 through 127 and interpreted as
+   US-ASCII characters [ASCII].  For brevity, this document sometimes
+   refers to this range of characters as simply "US-ASCII characters".
+
+
+
+
+
+Resnick                     Standards Track                     [Page 5]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   Note: This standard specifies that messages are made up of characters
+   in the US-ASCII range of 1 through 127.  There are other documents,
+   specifically the MIME document series [RFC2045, RFC2046, RFC2047,
+   RFC2048, RFC2049], that extend this standard to allow for values
+   outside of that range.  Discussion of those mechanisms is not within
+   the scope of this standard.
+
+   Messages are divided into lines of characters.  A line is a series of
+   characters that is delimited with the two characters carriage-return
+   and line-feed; that is, the carriage return (CR) character (ASCII
+   value 13) followed immediately by the line feed (LF) character (ASCII
+   value 10).  (The carriage-return/line-feed pair is usually written in
+   this document as "CRLF".)
+
+   A message consists of header fields (collectively called "the header
+   of the message") followed, optionally, by a body.  The header is a
+   sequence of lines of characters with special syntax as defined in
+   this standard. The body is simply a sequence of characters that
+   follows the header and is separated from the header by an empty line
+   (i.e., a line with nothing preceding the CRLF).
+
+2.1.1. Line Length Limits
+
+   There are two limits that this standard places on the number of
+   characters in a line. Each line of characters MUST be no more than
+   998 characters, and SHOULD be no more than 78 characters, excluding
+   the CRLF.
+
+   The 998 character limit is due to limitations in many implementations
+   which send, receive, or store Internet Message Format messages that
+   simply cannot handle more than 998 characters on a line. Receiving
+   implementations would do well to handle an arbitrarily large number
+   of characters in a line for robustness sake. However, there are so
+   many implementations which (in compliance with the transport
+   requirements of [RFC2821]) do not accept messages containing more
+   than 1000 character including the CR and LF per line, it is important
+   for implementations not to create such messages.
+
+   The more conservative 78 character recommendation is to accommodate
+   the many implementations of user interfaces that display these
+   messages which may truncate, or disastrously wrap, the display of
+   more than 78 characters per line, in spite of the fact that such
+   implementations are non-conformant to the intent of this
+   specification (and that of [RFC2821] if they actually cause
+   information to be lost). Again, even though this limitation is put on
+   messages, it is encumbant upon implementations which display messages
+
+
+
+
+
+Resnick                     Standards Track                     [Page 6]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   to handle an arbitrarily large number of characters in a line
+   (certainly at least up to the 998 character limit) for the sake of
+   robustness.
+
+2.2. Header Fields
+
+   Header fields are lines composed of a field name, followed by a colon
+   (":"), followed by a field body, and terminated by CRLF.  A field
+   name MUST be composed of printable US-ASCII characters (i.e.,
+   characters that have values between 33 and 126, inclusive), except
+   colon.  A field body may be composed of any US-ASCII characters,
+   except for CR and LF.  However, a field body may contain CRLF when
+   used in header "folding" and  "unfolding" as described in section
+   2.2.3.  All field bodies MUST conform to the syntax described in
+   sections 3 and 4 of this standard.
+
+2.2.1. Unstructured Header Field Bodies
+
+   Some field bodies in this standard are defined simply as
+   "unstructured" (which is specified below as any US-ASCII characters,
+   except for CR and LF) with no further restrictions.  These are
+   referred to as unstructured field bodies.  Semantically, unstructured
+   field bodies are simply to be treated as a single line of characters
+   with no further processing (except for header "folding" and
+   "unfolding" as described in section 2.2.3).
+
+2.2.2. Structured Header Field Bodies
+
+   Some field bodies in this standard have specific syntactical
+   structure more restrictive than the unstructured field bodies
+   described above. These are referred to as "structured" field bodies.
+   Structured field bodies are sequences of specific lexical tokens as
+   described in sections 3 and 4 of this standard.  Many of these tokens
+   are allowed (according to their syntax) to be introduced or end with
+   comments (as described in section 3.2.3) as well as the space (SP,
+   ASCII value 32) and horizontal tab (HTAB, ASCII value 9) characters
+   (together known as the white space characters, WSP), and those WSP
+   characters are subject to header "folding" and "unfolding" as
+   described in section 2.2.3.  Semantic analysis of structured field
+   bodies is given along with their syntax.
+
+2.2.3. Long Header Fields
+
+   Each header field is logically a single line of characters comprising
+   the field name, the colon, and the field body.  For convenience
+   however, and to deal with the 998/78 character limitations per line,
+   the field body portion of a header field can be split into a multiple
+   line representation; this is called "folding".  The general rule is
+
+
+
+Resnick                     Standards Track                     [Page 7]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   that wherever this standard allows for folding white space (not
+   simply WSP characters), a CRLF may be inserted before any WSP.  For
+   example, the header field:
+
+           Subject: This is a test
+
+   can be represented as:
+
+           Subject: This
+            is a test
+
+   Note: Though structured field bodies are defined in such a way that
+   folding can take place between many of the lexical tokens (and even
+   within some of the lexical tokens), folding SHOULD be limited to
+   placing the CRLF at higher-level syntactic breaks.  For instance, if
+   a field body is defined as comma-separated values, it is recommended
+   that folding occur after the comma separating the structured items in
+   preference to other places where the field could be folded, even if
+   it is allowed elsewhere.
+
+   The process of moving from this folded multiple-line representation
+   of a header field to its single line representation is called
+   "unfolding". Unfolding is accomplished by simply removing any CRLF
+   that is immediately followed by WSP.  Each header field should be
+   treated in its unfolded form for further syntactic and semantic
+   evaluation.
+
+2.3. Body
+
+   The body of a message is simply lines of US-ASCII characters.  The
+   only two limitations on the body are as follows:
+
+   - CR and LF MUST only occur together as CRLF; they MUST NOT appear
+     independently in the body.
+
+   - Lines of characters in the body MUST be limited to 998 characters,
+     and SHOULD be limited to 78 characters, excluding the CRLF.
+
+   Note: As was stated earlier, there are other standards documents,
+   specifically the MIME documents [RFC2045, RFC2046, RFC2048, RFC2049]
+   that extend this standard to allow for different sorts of message
+   bodies.  Again, these mechanisms are beyond the scope of this
+   document.
+
+
+
+
+
+
+
+
+Resnick                     Standards Track                     [Page 8]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+3. Syntax
+
+3.1. Introduction
+
+   The syntax as given in this section defines the legal syntax of
+   Internet messages.  Messages that are conformant to this standard
+   MUST conform to the syntax in this section.  If there are options in
+   this section where one option SHOULD be generated, that is indicated
+   either in the prose or in a comment next to the syntax.
+
+   For the defined expressions, a short description of the syntax and
+   use is given, followed by the syntax in ABNF, followed by a semantic
+   analysis.  Primitive tokens that are used but otherwise unspecified
+   come from [RFC2234].
+
+   In some of the definitions, there will be nonterminals whose names
+   start with "obs-".  These "obs-" elements refer to tokens defined in
+   the obsolete syntax in section 4.  In all cases, these productions
+   are to be ignored for the purposes of generating legal Internet
+   messages and MUST NOT be used as part of such a message.  However,
+   when interpreting messages, these tokens MUST be honored as part of
+   the legal syntax.  In this sense, section 3 defines a grammar for
+   generation of messages, with "obs-" elements that are to be ignored,
+   while section 4 adds grammar for interpretation of messages.
+
+3.2. Lexical Tokens
+
+   The following rules are used to define an underlying lexical
+   analyzer, which feeds tokens to the higher-level parsers.  This
+   section defines the tokens used in structured header field bodies.
+
+   Note: Readers of this standard need to pay special attention to how
+   these lexical tokens are used in both the lower-level and
+   higher-level syntax later in the document.  Particularly, the white
+   space tokens and the comment tokens defined in section 3.2.3 get used
+   in the lower-level tokens defined here, and those lower-level tokens
+   are in turn used as parts of the higher-level tokens defined later.
+   Therefore, the white space and comments may be allowed in the
+   higher-level tokens even though they may not explicitly appear in a
+   particular definition.
+
+3.2.1. Primitive Tokens
+
+   The following are primitive tokens referred to elsewhere in this
+   standard, but not otherwise defined in [RFC2234].  Some of them will
+   not appear anywhere else in the syntax, but they are convenient to
+   refer to in other parts of this document.
+
+
+
+
+Resnick                     Standards Track                     [Page 9]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   Note: The "specials" below are just such an example.  Though the
+   specials token does not appear anywhere else in this standard, it is
+   useful for implementers who use tools that lexically analyze
+   messages.  Each of the characters in specials can be used to indicate
+   a tokenization point in lexical analysis.
+
+NO-WS-CTL       =       %d1-8 /         ; US-ASCII control characters
+                        %d11 /          ;  that do not include the
+                        %d12 /          ;  carriage return, line feed,
+                        %d14-31 /       ;  and white space characters
+                        %d127
+
+text            =       %d1-9 /         ; Characters excluding CR and LF
+                        %d11 /
+                        %d12 /
+                        %d14-127 /
+                        obs-text
+
+specials        =       "(" / ")" /     ; Special characters used in
+                        "<" / ">" /     ;  other parts of the syntax
+                        "[" / "]" /
+                        ":" / ";" /
+                        "@" / "\" /
+                        "," / "." /
+                        DQUOTE
+
+   No special semantics are attached to these tokens.  They are simply
+   single characters.
+
+3.2.2. Quoted characters
+
+   Some characters are reserved for special interpretation, such as
+   delimiting lexical tokens.  To permit use of these characters as
+   uninterpreted data, a quoting mechanism is provided.
+
+quoted-pair     =       ("\" text) / obs-qp
+
+   Where any quoted-pair appears, it is to be interpreted as the text
+   character alone.  That is to say, the "\" character that appears as
+   part of a quoted-pair is semantically "invisible".
+
+   Note: The "\" character may appear in a message where it is not part
+   of a quoted-pair.  A "\" character that does not appear in a
+   quoted-pair is not semantically invisible.  The only places in this
+   standard where quoted-pair currently appears are ccontent, qcontent,
+   dcontent, no-fold-quote, and no-fold-literal.
+
+
+
+
+
+Resnick                     Standards Track                    [Page 10]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+3.2.3. Folding white space and comments
+
+   White space characters, including white space used in folding
+   (described in section 2.2.3), may appear between many elements in
+   header field bodies.  Also, strings of characters that are treated as
+   comments may be included in structured field bodies as characters
+   enclosed in parentheses.  The following defines the folding white
+   space (FWS) and comment constructs.
+
+   Strings of characters enclosed in parentheses are considered comments
+   so long as they do not appear within a "quoted-string", as defined in
+   section 3.2.5.  Comments may nest.
+
+   There are several places in this standard where comments and FWS may
+   be freely inserted.  To accommodate that syntax, an additional token
+   for "CFWS" is defined for places where comments and/or FWS can occur.
+   However, where CFWS occurs in this standard, it MUST NOT be inserted
+   in such a way that any line of a folded header field is made up
+   entirely of WSP characters and nothing else.
+
+FWS             =       ([*WSP CRLF] 1*WSP) /   ; Folding white space
+                        obs-FWS
+
+ctext           =       NO-WS-CTL /     ; Non white space controls
+
+                        %d33-39 /       ; The rest of the US-ASCII
+                        %d42-91 /       ;  characters not including "(",
+                        %d93-126        ;  ")", or "\"
+
+ccontent        =       ctext / quoted-pair / comment
+
+comment         =       "(" *([FWS] ccontent) [FWS] ")"
+
+CFWS            =       *([FWS] comment) (([FWS] comment) / FWS)
+
+   Throughout this standard, where FWS (the folding white space token)
+   appears, it indicates a place where header folding, as discussed in
+   section 2.2.3, may take place.  Wherever header folding appears in a
+   message (that is, a header field body containing a CRLF followed by
+   any WSP), header unfolding (removal of the CRLF) is performed before
+   any further lexical analysis is performed on that header field
+   according to this standard.  That is to say, any CRLF that appears in
+   FWS is semantically "invisible."
+
+   A comment is normally used in a structured field body to provide some
+   human readable informational text.  Since a comment is allowed to
+   contain FWS, folding is permitted within the comment.  Also note that
+   since quoted-pair is allowed in a comment, the parentheses and
+
+
+
+Resnick                     Standards Track                    [Page 11]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   backslash characters may appear in a comment so long as they appear
+   as a quoted-pair.  Semantically, the enclosing parentheses are not
+   part of the comment; the comment is what is contained between the two
+   parentheses.  As stated earlier, the "\" in any quoted-pair and the
+   CRLF in any FWS that appears within the comment are semantically
+   "invisible" and therefore not part of the comment either.
+
+   Runs of FWS, comment or CFWS that occur between lexical tokens in a
+   structured field header are semantically interpreted as a single
+   space character.
+
+3.2.4. Atom
+
+   Several productions in structured header field bodies are simply
+   strings of certain basic characters.  Such productions are called
+   atoms.
+
+   Some of the structured header field bodies also allow the period
+   character (".", ASCII value 46) within runs of atext.  An additional
+   "dot-atom" token is defined for those purposes.
+
+atext           =       ALPHA / DIGIT / ; Any character except controls,
+                        "!" / "#" /     ;  SP, and specials.
+                        "$" / "%" /     ;  Used for atoms
+                        "&" / "'" /
+                        "*" / "+" /
+                        "-" / "/" /
+                        "=" / "?" /
+                        "^" / "_" /
+                        "`" / "{" /
+                        "|" / "}" /
+                        "~"
+
+atom            =       [CFWS] 1*atext [CFWS]
+
+dot-atom        =       [CFWS] dot-atom-text [CFWS]
+
+dot-atom-text   =       1*atext *("." 1*atext)
+
+   Both atom and dot-atom are interpreted as a single unit, comprised of
+   the string of characters that make it up.  Semantically, the optional
+   comments and FWS surrounding the rest of the characters are not part
+   of the atom; the atom is only the run of atext characters in an atom,
+   or the atext and "." characters in a dot-atom.
+
+
+
+
+
+
+
+Resnick                     Standards Track                    [Page 12]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+3.2.5. Quoted strings
+
+   Strings of characters that include characters other than those
+   allowed in atoms may be represented in a quoted string format, where
+   the characters are surrounded by quote (DQUOTE, ASCII value 34)
+   characters.
+
+qtext           =       NO-WS-CTL /     ; Non white space controls
+
+                        %d33 /          ; The rest of the US-ASCII
+                        %d35-91 /       ;  characters not including "\"
+                        %d93-126        ;  or the quote character
+
+qcontent        =       qtext / quoted-pair
+
+quoted-string   =       [CFWS]
+                        DQUOTE *([FWS] qcontent) [FWS] DQUOTE
+                        [CFWS]
+
+   A quoted-string is treated as a unit.  That is, quoted-string is
+   identical to atom, semantically.  Since a quoted-string is allowed to
+   contain FWS, folding is permitted.  Also note that since quoted-pair
+   is allowed in a quoted-string, the quote and backslash characters may
+   appear in a quoted-string so long as they appear as a quoted-pair.
+
+   Semantically, neither the optional CFWS outside of the quote
+   characters nor the quote characters themselves are part of the
+   quoted-string; the quoted-string is what is contained between the two
+   quote characters.  As stated earlier, the "\" in any quoted-pair and
+   the CRLF in any FWS/CFWS that appears within the quoted-string are
+   semantically "invisible" and therefore not part of the quoted-string
+   either.
+
+3.2.6. Miscellaneous tokens
+
+   Three additional tokens are defined, word and phrase for combinations
+   of atoms and/or quoted-strings, and unstructured for use in
+   unstructured header fields and in some places within structured
+   header fields.
+
+word            =       atom / quoted-string
+
+phrase          =       1*word / obs-phrase
+
+
+
+
+
+
+
+
+Resnick                     Standards Track                    [Page 13]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+utext           =       NO-WS-CTL /     ; Non white space controls
+                        %d33-126 /      ; The rest of US-ASCII
+                        obs-utext
+
+unstructured    =       *([FWS] utext) [FWS]
+
+3.3. Date and Time Specification
+
+   Date and time occur in several header fields.  This section specifies
+   the syntax for a full date and time specification.  Though folding
+   white space is permitted throughout the date-time specification, it
+   is RECOMMENDED that a single space be used in each place that FWS
+   appears (whether it is required or optional); some older
+   implementations may not interpret other occurrences of folding white
+   space correctly.
+
+date-time       =       [ day-of-week "," ] date FWS time [CFWS]
+
+day-of-week     =       ([FWS] day-name) / obs-day-of-week
+
+day-name        =       "Mon" / "Tue" / "Wed" / "Thu" /
+                        "Fri" / "Sat" / "Sun"
+
+date            =       day month year
+
+year            =       4*DIGIT / obs-year
+
+month           =       (FWS month-name FWS) / obs-month
+
+month-name      =       "Jan" / "Feb" / "Mar" / "Apr" /
+                        "May" / "Jun" / "Jul" / "Aug" /
+                        "Sep" / "Oct" / "Nov" / "Dec"
+
+day             =       ([FWS] 1*2DIGIT) / obs-day
+
+time            =       time-of-day FWS zone
+
+time-of-day     =       hour ":" minute [ ":" second ]
+
+hour            =       2DIGIT / obs-hour
+
+minute          =       2DIGIT / obs-minute
+
+second          =       2DIGIT / obs-second
+
+zone            =       (( "+" / "-" ) 4DIGIT) / obs-zone
+
+
+
+
+
+Resnick                     Standards Track                    [Page 14]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   The day is the numeric day of the month.  The year is any numeric
+   year 1900 or later.
+
+   The time-of-day specifies the number of hours, minutes, and
+   optionally seconds since midnight of the date indicated.
+
+   The date and time-of-day SHOULD express local time.
+
+   The zone specifies the offset from Coordinated Universal Time (UTC,
+   formerly referred to as "Greenwich Mean Time") that the date and
+   time-of-day represent.  The "+" or "-" indicates whether the
+   time-of-day is ahead of (i.e., east of) or behind (i.e., west of)
+   Universal Time.  The first two digits indicate the number of hours
+   difference from Universal Time, and the last two digits indicate the
+   number of minutes difference from Universal Time.  (Hence, +hhmm
+   means +(hh * 60 + mm) minutes, and -hhmm means -(hh * 60 + mm)
+   minutes).  The form "+0000" SHOULD be used to indicate a time zone at
+   Universal Time.  Though "-0000" also indicates Universal Time, it is
+   used to indicate that the time was generated on a system that may be
+   in a local time zone other than Universal Time and therefore
+   indicates that the date-time contains no information about the local
+   time zone.
+
+   A date-time specification MUST be semantically valid.  That is, the
+   day-of-the-week (if included) MUST be the day implied by the date,
+   the numeric day-of-month MUST be between 1 and the number of days
+   allowed for the specified month (in the specified year), the
+   time-of-day MUST be in the range 00:00:00 through 23:59:60 (the
+   number of seconds allowing for a leap second; see [STD12]), and the
+   zone MUST be within the range -9959 through +9959.
+
+3.4. Address Specification
+
+   Addresses occur in several message header fields to indicate senders
+   and recipients of messages.  An address may either be an individual
+   mailbox, or a group of mailboxes.
+
+address         =       mailbox / group
+
+mailbox         =       name-addr / addr-spec
+
+name-addr       =       [display-name] angle-addr
+
+angle-addr      =       [CFWS] "<" addr-spec ">" [CFWS] / obs-angle-addr
+
+group           =       display-name ":" [mailbox-list / CFWS] ";"
+                        [CFWS]
+
+
+
+
+Resnick                     Standards Track                    [Page 15]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+display-name    =       phrase
+
+mailbox-list    =       (mailbox *("," mailbox)) / obs-mbox-list
+
+address-list    =       (address *("," address)) / obs-addr-list
+
+   A mailbox receives mail.  It is a conceptual entity which does not
+   necessarily pertain to file storage.  For example, some sites may
+   choose to print mail on a printer and deliver the output to the
+   addressee's desk.  Normally, a mailbox is comprised of two parts: (1)
+   an optional display name that indicates the name of the recipient
+   (which could be a person or a system) that could be displayed to the
+   user of a mail application, and (2) an addr-spec address enclosed in
+   angle brackets ("<" and ">").  There is also an alternate simple form
+   of a mailbox where the addr-spec address appears alone, without the
+   recipient's name or the angle brackets.  The Internet addr-spec
+   address is described in section 3.4.1.
+
+   Note: Some legacy implementations used the simple form where the
+   addr-spec appears without the angle brackets, but included the name
+   of the recipient in parentheses as a comment following the addr-spec.
+   Since the meaning of the information in a comment is unspecified,
+   implementations SHOULD use the full name-addr form of the mailbox,
+   instead of the legacy form, to specify the display name associated
+   with a mailbox.  Also, because some legacy implementations interpret
+   the comment, comments generally SHOULD NOT be used in address fields
+   to avoid confusing such implementations.
+
+   When it is desirable to treat several mailboxes as a single unit
+   (i.e., in a distribution list), the group construct can be used.  The
+   group construct allows the sender to indicate a named group of
+   recipients. This is done by giving a display name for the group,
+   followed by a colon, followed by a comma separated list of any number
+   of mailboxes (including zero and one), and ending with a semicolon.
+   Because the list of mailboxes can be empty, using the group construct
+   is also a simple way to communicate to recipients that the message
+   was sent to one or more named sets of recipients, without actually
+   providing the individual mailbox address for each of those
+   recipients.
+
+3.4.1. Addr-spec specification
+
+   An addr-spec is a specific Internet identifier that contains a
+   locally interpreted string followed by the at-sign character ("@",
+   ASCII value 64) followed by an Internet domain.  The locally
+   interpreted string is either a quoted-string or a dot-atom.  If the
+   string can be represented as a dot-atom (that is, it contains no
+   characters other than atext characters or "." surrounded by atext
+
+
+
+Resnick                     Standards Track                    [Page 16]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   characters), then the dot-atom form SHOULD be used and the
+   quoted-string form SHOULD NOT be used. Comments and folding white
+   space SHOULD NOT be used around the "@" in the addr-spec.
+
+addr-spec       =       local-part "@" domain
+
+local-part      =       dot-atom / quoted-string / obs-local-part
+
+domain          =       dot-atom / domain-literal / obs-domain
+
+domain-literal  =       [CFWS] "[" *([FWS] dcontent) [FWS] "]" [CFWS]
+
+dcontent        =       dtext / quoted-pair
+
+dtext           =       NO-WS-CTL /     ; Non white space controls
+
+                        %d33-90 /       ; The rest of the US-ASCII
+                        %d94-126        ;  characters not including "[",
+                                        ;  "]", or "\"
+
+   The domain portion identifies the point to which the mail is
+   delivered. In the dot-atom form, this is interpreted as an Internet
+   domain name (either a host name or a mail exchanger name) as
+   described in [STD3, STD13, STD14].  In the domain-literal form, the
+   domain is interpreted as the literal Internet address of the
+   particular host.  In both cases, how addressing is used and how
+   messages are transported to a particular host is covered in the mail
+   transport document [RFC2821].  These mechanisms are outside of the
+   scope of this document.
+
+   The local-part portion is a domain dependent string.  In addresses,
+   it is simply interpreted on the particular host as a name of a
+   particular mailbox.
+
+3.5 Overall message syntax
+
+   A message consists of header fields, optionally followed by a message
+   body.  Lines in a message MUST be a maximum of 998 characters
+   excluding the CRLF, but it is RECOMMENDED that lines be limited to 78
+   characters excluding the CRLF.  (See section 2.1.1 for explanation.)
+   In a message body, though all of the characters listed in the text
+   rule MAY be used, the use of US-ASCII control characters (values 1
+   through 8, 11, 12, and 14 through 31) is discouraged since their
+   interpretation by receivers for display is not guaranteed.
+
+
+
+
+
+
+
+Resnick                     Standards Track                    [Page 17]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+message         =       (fields / obs-fields)
+                        [CRLF body]
+
+body            =       *(*998text CRLF) *998text
+
+   The header fields carry most of the semantic information and are
+   defined in section 3.6.  The body is simply a series of lines of text
+   which are uninterpreted for the purposes of this standard.
+
+3.6. Field definitions
+
+   The header fields of a message are defined here.  All header fields
+   have the same general syntactic structure: A field name, followed by
+   a colon, followed by the field body.  The specific syntax for each
+   header field is defined in the subsequent sections.
+
+   Note: In the ABNF syntax for each field in subsequent sections, each
+   field name is followed by the required colon.  However, for brevity
+   sometimes the colon is not referred to in the textual description of
+   the syntax.  It is, nonetheless, required.
+
+   It is important to note that the header fields are not guaranteed to
+   be in a particular order.  They may appear in any order, and they
+   have been known to be reordered occasionally when transported over
+   the Internet.  However, for the purposes of this standard, header
+   fields SHOULD NOT be reordered when a message is transported or
+   transformed.  More importantly, the trace header fields and resent
+   header fields MUST NOT be reordered, and SHOULD be kept in blocks
+   prepended to the message.  See sections 3.6.6 and 3.6.7 for more
+   information.
+
+   The only required header fields are the origination date field and
+   the originator address field(s).  All other header fields are
+   syntactically optional.  More information is contained in the table
+   following this definition.
+
+fields          =       *(trace
+                          *(resent-date /
+                           resent-from /
+                           resent-sender /
+                           resent-to /
+                           resent-cc /
+                           resent-bcc /
+                           resent-msg-id))
+                        *(orig-date /
+                        from /
+                        sender /
+                        reply-to /
+
+
+
+Resnick                     Standards Track                    [Page 18]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+                        to /
+                        cc /
+                        bcc /
+                        message-id /
+                        in-reply-to /
+                        references /
+                        subject /
+                        comments /
+                        keywords /
+                        optional-field)
+
+   The following table indicates limits on the number of times each
+   field may occur in a message header as well as any special
+   limitations on the use of those fields.  An asterisk next to a value
+   in the minimum or maximum column indicates that a special restriction
+   appears in the Notes column.
+
+Field           Min number      Max number      Notes
+
+trace           0               unlimited       Block prepended - see
+                                                3.6.7
+
+resent-date     0*              unlimited*      One per block, required
+                                                if other resent fields
+                                                present - see 3.6.6
+
+resent-from     0               unlimited*      One per block - see
+                                                3.6.6
+
+resent-sender   0*              unlimited*      One per block, MUST
+                                                occur with multi-address
+                                                resent-from - see 3.6.6
+
+resent-to       0               unlimited*      One per block - see
+                                                3.6.6
+
+resent-cc       0               unlimited*      One per block - see
+                                                3.6.6
+
+resent-bcc      0               unlimited*      One per block - see
+                                                3.6.6
+
+resent-msg-id   0               unlimited*      One per block - see
+                                                3.6.6
+
+orig-date       1               1
+
+from            1               1               See sender and 3.6.2
+
+
+
+Resnick                     Standards Track                    [Page 19]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+sender          0*              1               MUST occur with multi-
+                                                address from - see 3.6.2
+
+reply-to        0               1
+
+to              0               1
+
+cc              0               1
+
+bcc             0               1
+
+message-id      0*              1               SHOULD be present - see
+                                                3.6.4
+
+in-reply-to     0*              1               SHOULD occur in some
+                                                replies - see 3.6.4
+
+references      0*              1               SHOULD occur in some
+                                                replies - see 3.6.4
+
+subject         0               1
+
+comments        0               unlimited
+
+keywords        0               unlimited
+
+optional-field  0               unlimited
+
+   The exact interpretation of each field is described in subsequent
+   sections.
+
+3.6.1. The origination date field
+
+   The origination date field consists of the field name "Date" followed
+   by a date-time specification.
+
+orig-date       =       "Date:" date-time CRLF
+
+   The origination date 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.  For instance, this might be the time
+   that a user pushes the "send" or "submit" button in an application
+   program.  In any case, it is specifically not intended to convey the
+   time that the message is actually transported, but rather the time at
+   which the human or other creator of the message has put the message
+   into its final form, ready for transport.  (For example, a portable
+   computer user who is not connected to a network might queue a message
+
+
+
+
+Resnick                     Standards Track                    [Page 20]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   for delivery.  The origination date is intended to contain the date
+   and time that the user queued the message, not the time when the user
+   connected to the network to send the message.)
+
+3.6.2. Originator fields
+
+   The originator fields of a message consist of the from field, the
+   sender field (when applicable), and optionally the reply-to field.
+   The from field consists of the field name "From" and a
+   comma-separated list of one or more mailbox specifications.  If the
+   from field contains more than one mailbox specification in the
+   mailbox-list, then the sender field, containing the field name
+   "Sender" and a single mailbox specification, MUST appear in the
+   message.  In either case, an optional reply-to field MAY also be
+   included, which contains the field name "Reply-To" and a
+   comma-separated list of one or more addresses.
+
+from            =       "From:" mailbox-list CRLF
+
+sender          =       "Sender:" mailbox CRLF
+
+reply-to        =       "Reply-To:" address-list CRLF
+
+   The originator fields indicate the mailbox(es) of the source of the
+   message.  The "From:" field 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.  The "Sender:" field specifies the
+   mailbox of the agent responsible for the actual transmission of the
+   message.  For example, if a secretary were to send a message for
+   another person, the mailbox of the secretary would appear in the
+   "Sender:" field and the mailbox of the actual author would appear in
+   the "From:" field.  If the originator of the message can be indicated
+   by a single mailbox and the author and transmitter are identical, the
+   "Sender:" field SHOULD NOT be used.  Otherwise, both fields SHOULD
+   appear.
+
+   The originator fields also provide the information required when
+   replying to a message.  When the "Reply-To:" field is present, it
+   indicates the mailbox(es) to which the author of the message suggests
+   that replies be sent.  In the absence of the "Reply-To:" field,
+   replies SHOULD by default be sent to the mailbox(es) specified in the
+   "From:" field unless otherwise specified by the person composing the
+   reply.
+
+   In all cases, the "From:" field SHOULD NOT contain any mailbox that
+   does not belong to the author(s) of the message.  See also section
+   3.6.3 for more information on forming the destination addresses for a
+   reply.
+
+
+
+Resnick                     Standards Track                    [Page 21]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+3.6.3. Destination address fields
+
+   The destination fields of a message consist of three possible fields,
+   each of the same form: The field name, which is either "To", "Cc", or
+   "Bcc", followed by a comma-separated list of one or more addresses
+   (either mailbox or group syntax).
+
+to              =       "To:" address-list CRLF
+
+cc              =       "Cc:" address-list CRLF
+
+bcc             =       "Bcc:" (address-list / [CFWS]) CRLF
+
+   The destination fields specify the recipients of the message.  Each
+   destination field may have one or more addresses, and each of the
+   addresses indicate the intended recipients of the message.  The only
+   difference between the three fields is how each is used.
+
+   The "To:" field contains the address(es) of the primary recipient(s)
+   of the message.
+
+   The "Cc:" field (where the "Cc" means "Carbon Copy" in the sense of
+   making a copy on a typewriter using carbon paper) contains the
+   addresses of others who are to receive the message, though the
+   content of the message may not be directed at them.
+
+   The "Bcc:" field (where the "Bcc" means "Blind Carbon Copy") contains
+   addresses of recipients of the message whose addresses are not to be
+   revealed to other recipients of the message.  There are three ways in
+   which the "Bcc:" field is used.  In the first case, when a message
+   containing a "Bcc:" field is prepared to be sent, the "Bcc:" line is
+   removed even though all of the recipients (including those specified
+   in the "Bcc:" field) are sent a copy of the message.  In the second
+   case, recipients specified in the "To:" and "Cc:" lines each are sent
+   a copy of the message with the "Bcc:" line removed as above, but the
+   recipients on the "Bcc:" line get a separate copy of the message
+   containing a "Bcc:" line.  (When there are multiple recipient
+   addresses in the "Bcc:" field, some implementations actually send a
+   separate copy of the message to each recipient with a "Bcc:"
+   containing only the address of that particular recipient.) Finally,
+   since a "Bcc:" field may contain no addresses, a "Bcc:" field can be
+   sent without any addresses indicating to the recipients that blind
+   copies were sent to someone.  Which method to use with "Bcc:" fields
+   is implementation dependent, but refer to the "Security
+   Considerations" section of this document for a discussion of each.
+
+
+
+
+
+
+Resnick                     Standards Track                    [Page 22]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   When a message is a reply to another message, the mailboxes of the
+   authors of the original message (the mailboxes in the "From:" field)
+   or mailboxes specified in the "Reply-To:" field (if it exists) MAY
+   appear in the "To:" field of the reply since these would normally be
+   the primary recipients of the reply.  If a reply is sent to a message
+   that has destination fields, it is often desirable to send a copy of
+   the reply to all of the recipients of the message, in addition to the
+   author.  When such a reply is formed, addresses in the "To:" and
+   "Cc:" fields of the original message MAY appear in the "Cc:" field of
+   the reply, since these are normally secondary recipients of the
+   reply.  If a "Bcc:" field is present in the original message,
+   addresses in that field MAY appear in the "Bcc:" field of the reply,
+   but SHOULD NOT appear in the "To:" or "Cc:" fields.
+
+   Note: Some mail applications have automatic reply commands that
+   include the destination addresses of the original message in the
+   destination addresses of the reply.  How those reply commands behave
+   is implementation dependent and is beyond the scope of this document.
+   In particular, whether or not to include the original destination
+   addresses when the original message had a "Reply-To:" field is not
+   addressed here.
+
+3.6.4. Identification fields
+
+   Though optional, every message SHOULD have a "Message-ID:" field.
+   Furthermore, reply messages SHOULD have "In-Reply-To:" and
+   "References:" fields as appropriate, as described below.
+
+   The "Message-ID:" field contains a single unique message identifier.
+   The "References:" and "In-Reply-To:" field each contain one or more
+   unique message identifiers, optionally separated by CFWS.
+
+   The message identifier (msg-id) is similar in syntax to an angle-addr
+   construct without the internal CFWS.
+
+message-id      =       "Message-ID:" msg-id CRLF
+
+in-reply-to     =       "In-Reply-To:" 1*msg-id CRLF
+
+references      =       "References:" 1*msg-id CRLF
+
+msg-id          =       [CFWS] "<" id-left "@" id-right ">" [CFWS]
+
+id-left         =       dot-atom-text / no-fold-quote / obs-id-left
+
+id-right        =       dot-atom-text / no-fold-literal / obs-id-right
+
+no-fold-quote   =       DQUOTE *(qtext / quoted-pair) DQUOTE
+
+
+
+Resnick                     Standards Track                    [Page 23]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+no-fold-literal =       "[" *(dtext / quoted-pair) "]"
+
+   The "Message-ID:" field provides a unique message identifier that
+   refers to a particular version of a particular message.  The
+   uniqueness of the message identifier is guaranteed by the host that
+   generates it (see below).  This message identifier is intended to be
+   machine readable and not necessarily meaningful to humans.  A message
+   identifier pertains to exactly one instantiation of a particular
+   message; subsequent revisions to the message each receive new message
+   identifiers.
+
+   Note: There are many instances when messages are "changed", but those
+   changes do not constitute a new instantiation of that message, and
+   therefore the message would not get a new message identifier.  For
+   example, when messages are introduced into the transport system, they
+   are often prepended with additional header fields such as trace
+   fields (described in section 3.6.7) and resent fields (described in
+   section 3.6.6).  The addition of such header fields does not change
+   the identity of the message and therefore the original "Message-ID:"
+   field is retained.  In all cases, it is the meaning that the sender
+   of the message wishes to convey (i.e., whether this is the same
+   message or a different message) that determines whether or not the
+   "Message-ID:" field changes, not any particular syntactic difference
+   that appears (or does not appear) in the message.
+
+   The "In-Reply-To:" and "References:" fields are used when creating a
+   reply to a message.  They hold the message identifier of the original
+   message and the message identifiers of other messages (for example,
+   in the case of a reply to a message which was itself a reply).  The
+   "In-Reply-To:" field may be used to identify the message (or
+   messages) to which the new message is a reply, while the
+   "References:" field may be used to identify a "thread" of
+   conversation.
+
+   When creating a reply to a message, the "In-Reply-To:" and
+   "References:" fields of the resultant message are constructed as
+   follows:
+
+   The "In-Reply-To:" field will contain the contents of the "Message-
+   ID:" field of the message to which this one is a reply (the "parent
+   message").  If there is more than one parent message, then the "In-
+   Reply-To:" field will contain the contents of all of the parents'
+   "Message-ID:" fields.  If there is no "Message-ID:" field in any of
+   the parent messages, then the new message will have no "In-Reply-To:"
+   field.
+
+
+
+
+
+
+Resnick                     Standards Track                    [Page 24]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   The "References:" field will contain the contents of the parent's
+   "References:" field (if any) followed by the contents of the parent's
+   "Message-ID:" field (if any).  If the parent message does not contain
+   a "References:" field but does have an "In-Reply-To:" field
+   containing a single message identifier, then the "References:" field
+   will contain the contents of the parent's "In-Reply-To:" field
+   followed by the contents of the parent's "Message-ID:" field (if
+   any).  If the parent has none of the "References:", "In-Reply-To:",
+   or "Message-ID:" fields, then the new message will have no
+   "References:" field.
+
+   Note: Some implementations parse the "References:" field to display
+   the "thread of the discussion".  These implementations assume that
+   each new message is a reply to a single parent and hence that they
+   can walk backwards through the "References:" field to find the parent
+   of each message listed there.  Therefore, trying to form a
+   "References:" field for a reply that has multiple parents is
+   discouraged and how to do so is not defined in this document.
+
+   The message identifier (msg-id) itself MUST be a globally unique
+   identifier for a message.  The generator of the message identifier
+   MUST guarantee that the msg-id is unique.  There are several
+   algorithms that can be used to accomplish this.  Since the msg-id has
+   a similar syntax to angle-addr (identical except that comments and
+   folding white space are not allowed), a good method is to put the
+   domain name (or a domain literal IP address) of the host on which the
+   message identifier was created on the right hand side of the "@", and
+   put a combination of the current absolute date and time along with
+   some other currently unique (perhaps sequential) identifier available
+   on the system (for example, a process id number) on the left hand
+   side.  Using a date on the left hand side and a domain name or domain
+   literal on the right hand side makes it possible to guarantee
+   uniqueness since no two hosts use the same domain name or IP address
+   at the same time.  Though other algorithms will work, it is
+   RECOMMENDED that the right hand side contain some domain identifier
+   (either of the host itself or otherwise) such that the generator of
+   the message identifier can guarantee the uniqueness of the left hand
+   side within the scope of that domain.
+
+   Semantically, the angle bracket characters are not part of the
+   msg-id; the msg-id is what is contained between the two angle bracket
+   characters.
+
+
+
+
+
+
+
+
+
+Resnick                     Standards Track                    [Page 25]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+3.6.5. Informational fields
+
+   The informational fields are all optional.  The "Keywords:" field
+   contains a comma-separated list of one or more words or
+   quoted-strings. The "Subject:" and "Comments:" fields are
+   unstructured fields as defined in section 2.2.1, and therefore may
+   contain text or folding white space.
+
+subject         =       "Subject:" unstructured CRLF
+
+comments        =       "Comments:" unstructured CRLF
+
+keywords        =       "Keywords:" phrase *("," phrase) CRLF
+
+   These three fields are intended to have only human-readable content
+   with information about the message.  The "Subject:" field is the most
+   common and contains a short string identifying the topic of the
+   message.  When used in a reply, the field body MAY start with the
+   string "Re: " (from the Latin "res", in the matter of) followed by
+   the contents of the "Subject:" field body of the original message.
+   If this is done, only one instance of the literal string "Re: " ought
+   to be used since use of other strings or more than one instance can
+   lead to undesirable consequences.  The "Comments:" field contains any
+   additional comments on the text of the body of the message.  The
+   "Keywords:" field contains a comma-separated list of important words
+   and phrases that might be useful for the recipient.
+
+3.6.6. Resent fields
+
+   Resent fields SHOULD be added to any message that is reintroduced by
+   a user into the transport system.  A separate set of resent fields
+   SHOULD be added each time this is done.  All of the resent fields
+   corresponding to a particular resending of the message SHOULD be
+   together.  Each new set of resent fields is prepended to the message;
+   that is, the most recent set of resent fields appear earlier in the
+   message.  No other fields in the message are changed when resent
+   fields are added.
+
+   Each of the resent fields corresponds to a particular field elsewhere
+   in the syntax.  For instance, the "Resent-Date:" field corresponds to
+   the "Date:" field and the "Resent-To:" field corresponds to the "To:"
+   field.  In each case, the syntax for the field body is identical to
+   the syntax given previously for the corresponding field.
+
+   When resent fields are used, the "Resent-From:" and "Resent-Date:"
+   fields MUST be sent.  The "Resent-Message-ID:" field SHOULD be sent.
+   "Resent-Sender:" SHOULD NOT be used if "Resent-Sender:" would be
+   identical to "Resent-From:".
+
+
+
+Resnick                     Standards Track                    [Page 26]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+resent-date     =       "Resent-Date:" date-time CRLF
+
+resent-from     =       "Resent-From:" mailbox-list CRLF
+
+resent-sender   =       "Resent-Sender:" mailbox CRLF
+
+resent-to       =       "Resent-To:" address-list CRLF
+
+resent-cc       =       "Resent-Cc:" address-list CRLF
+
+resent-bcc      =       "Resent-Bcc:" (address-list / [CFWS]) CRLF
+
+resent-msg-id   =       "Resent-Message-ID:" msg-id CRLF
+
+   Resent fields are used to identify a message as having been
+   reintroduced into the transport system by a user.  The purpose of
+   using resent fields is to have the message appear to the final
+   recipient as if it were sent directly by the original sender, with
+   all of the original fields remaining the same.  Each set of resent
+   fields correspond to a particular resending event.  That is, if a
+   message is resent multiple times, each set of resent fields gives
+   identifying information for each individual time.  Resent fields are
+   strictly informational.  They MUST NOT be used in the normal
+   processing of replies or other such automatic actions on messages.
+
+   Note: Reintroducing a message into the transport system and using
+   resent fields is a different operation from "forwarding".
+   "Forwarding" has two meanings: One sense of forwarding is that a mail
+   reading program can be told by a user to forward a copy of a message
+   to another person, making the forwarded message the body of the new
+   message.  A forwarded message in this sense does not appear to have
+   come from the original sender, but is an entirely new message from
+   the forwarder of the message.  On the other hand, forwarding is also
+   used to mean when a mail transport program gets a message and
+   forwards it on to a different destination for final delivery.  Resent
+   header fields are not intended for use with either type of
+   forwarding.
+
+   The resent originator fields indicate the mailbox of the person(s) or
+   system(s) that resent the message.  As with the regular originator
+   fields, there are two forms: a simple "Resent-From:" form which
+   contains the mailbox of the individual doing the resending, and the
+   more complex form, when one individual (identified in the
+   "Resent-Sender:" field) resends a message on behalf of one or more
+   others (identified in the "Resent-From:" field).
+
+   Note: When replying to a resent message, replies behave just as they
+   would with any other message, using the original "From:",
+
+
+
+Resnick                     Standards Track                    [Page 27]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   "Reply-To:", "Message-ID:", and other fields.  The resent fields are
+   only informational and MUST NOT be used in the normal processing of
+   replies.
+
+   The "Resent-Date:" indicates the date and time at which the resent
+   message is dispatched by the resender of the message.  Like the
+   "Date:" field, it is not the date and time that the message was
+   actually transported.
+
+   The "Resent-To:", "Resent-Cc:", and "Resent-Bcc:" fields function
+   identically to the "To:", "Cc:", and "Bcc:" fields respectively,
+   except that they indicate the recipients of the resent message, not
+   the recipients of the original message.
+
+   The "Resent-Message-ID:" field provides a unique identifier for the
+   resent message.
+
+3.6.7. Trace fields
+
+   The trace fields are a group of header fields consisting of an
+   optional "Return-Path:" field, and one or more "Received:" fields.
+   The "Return-Path:" header field contains a pair of angle brackets
+   that enclose an optional addr-spec.  The "Received:" field contains a
+   (possibly empty) list of name/value pairs followed by a semicolon and
+   a date-time specification.  The first item of the name/value pair is
+   defined by item-name, and the second item is either an addr-spec, an
+   atom, a domain, or a msg-id.  Further restrictions may be applied to
+   the syntax of the trace fields by standards that provide for their
+   use, such as [RFC2821].
+
+trace           =       [return]
+                        1*received
+
+return          =       "Return-Path:" path CRLF
+
+path            =       ([CFWS] "<" ([CFWS] / addr-spec) ">" [CFWS]) /
+                        obs-path
+
+received        =       "Received:" name-val-list ";" date-time CRLF
+
+name-val-list   =       [CFWS] [name-val-pair *(CFWS name-val-pair)]
+
+name-val-pair   =       item-name CFWS item-value
+
+item-name       =       ALPHA *(["-"] (ALPHA / DIGIT))
+
+item-value      =       1*angle-addr / addr-spec /
+                         atom / domain / msg-id
+
+
+
+Resnick                     Standards Track                    [Page 28]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   A full discussion of the Internet mail use of trace fields is
+   contained in [RFC2821].  For the purposes of this standard, the trace
+   fields are strictly informational, and any formal interpretation of
+   them is outside of the scope of this document.
+
+3.6.8. Optional fields
+
+   Fields may appear in messages that are otherwise unspecified in this
+   standard.  They MUST conform to the syntax of an optional-field.
+   This is a field name, made up of the printable US-ASCII characters
+   except SP and colon, followed by a colon, followed by any text which
+   conforms to unstructured.
+
+   The field names of any optional-field MUST NOT be identical to any
+   field name specified elsewhere in this standard.
+
+optional-field  =       field-name ":" unstructured CRLF
+
+field-name      =       1*ftext
+
+ftext           =       %d33-57 /               ; Any character except
+                        %d59-126                ;  controls, SP, and
+                                                ;  ":".
+
+   For the purposes of this standard, any optional field is
+   uninterpreted.
+
+4. Obsolete Syntax
+
+   Earlier versions of this standard allowed for different (usually more
+   liberal) syntax than is allowed in this version.  Also, there have
+   been syntactic elements used in messages on the Internet whose
+   interpretation have never been documented.  Though some of these
+   syntactic forms MUST NOT be generated according to the grammar in
+   section 3, they MUST be accepted and parsed by a conformant receiver.
+   This section documents many of these syntactic elements.  Taking the
+   grammar in section 3 and adding the definitions presented in this
+   section will result in the grammar to use for interpretation of
+   messages.
+
+   Note: This section identifies syntactic forms that any implementation
+   MUST reasonably interpret.  However, there are certainly Internet
+   messages which do not conform to even the additional syntax given in
+   this section.  The fact that a particular form does not appear in any
+   section of this document is not justification for computer programs
+   to crash or for malformed data to be irretrievably lost by any
+   implementation.  To repeat an example, though this document requires
+   lines in messages to be no longer than 998 characters, silently
+
+
+
+Resnick                     Standards Track                    [Page 29]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   discarding the 999th and subsequent characters in a line without
+   warning would still be bad behavior for an implementation.  It is up
+   to the implementation to deal with messages robustly.
+
+   One important difference between the obsolete (interpreting) and the
+   current (generating) syntax is that in structured header field bodies
+   (i.e., between the colon and the CRLF of any structured header
+   field), white space characters, including folding white space, and
+   comments can be freely inserted between any syntactic tokens.  This
+   allows many complex forms that have proven difficult for some
+   implementations to parse.
+
+   Another key difference between the obsolete and the current syntax is
+   that the rule in section 3.2.3 regarding lines composed entirely of
+   white space in comments and folding white space does not apply.  See
+   the discussion of folding white space in section 4.2 below.
+
+   Finally, certain characters that were formerly allowed in messages
+   appear in this section.  The NUL character (ASCII value 0) was once
+   allowed, but is no longer for compatibility reasons.  CR and LF were
+   allowed to appear in messages other than as CRLF; this use is also
+   shown here.
+
+   Other differences in syntax and semantics are noted in the following
+   sections.
+
+4.1. Miscellaneous obsolete tokens
+
+   These syntactic elements are used elsewhere in the obsolete syntax or
+   in the main syntax.  The obs-char and obs-qp elements each add ASCII
+   value 0. Bare CR and bare LF are added to obs-text and obs-utext.
+   The period character is added to obs-phrase. The obs-phrase-list
+   provides for "empty" elements in a comma-separated list of phrases.
+
+   Note: The "period" (or "full stop") character (".") in obs-phrase is
+   not a form that was allowed in earlier versions of this or any other
+   standard.  Period (nor any other character from specials) was not
+   allowed in phrase because it introduced a parsing difficulty
+   distinguishing between phrases and portions of an addr-spec (see
+   section 4.4).  It appears here because the period character is
+   currently used in many messages in the display-name portion of
+   addresses, especially for initials in names, and therefore must be
+   interpreted properly.  In the future, period may appear in the
+   regular syntax of phrase.
+
+obs-qp          =       "\" (%d0-127)
+
+obs-text        =       *LF *CR *(obs-char *LF *CR)
+
+
+
+Resnick                     Standards Track                    [Page 30]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+obs-char        =       %d0-9 / %d11 /          ; %d0-127 except CR and
+                        %d12 / %d14-127         ;  LF
+
+obs-utext       =       obs-text
+
+obs-phrase      =       word *(word / "." / CFWS)
+
+obs-phrase-list =       phrase / 1*([phrase] [CFWS] "," [CFWS]) [phrase]
+
+   Bare CR and bare LF appear in messages with two different meanings.
+   In many cases, bare CR or bare LF are used improperly instead of CRLF
+   to indicate line separators.  In other cases, bare CR and bare LF are
+   used simply as ASCII control characters with their traditional ASCII
+   meanings.
+
+4.2. Obsolete folding white space
+
+   In the obsolete syntax, any amount of folding white space MAY be
+   inserted where the obs-FWS rule is allowed.  This creates the
+   possibility of having two consecutive "folds" in a line, and
+   therefore the possibility that a line which makes up a folded header
+   field could be composed entirely of white space.
+
+   obs-FWS         =       1*WSP *(CRLF 1*WSP)
+
+4.3. Obsolete Date and Time
+
+   The syntax for the obsolete date format allows a 2 digit year in the
+   date field and allows for a list of alphabetic time zone
+   specifications that were used in earlier versions of this standard.
+   It also permits comments and folding white space between many of the
+   tokens.
+
+obs-day-of-week =       [CFWS] day-name [CFWS]
+
+obs-year        =       [CFWS] 2*DIGIT [CFWS]
+
+obs-month       =       CFWS month-name CFWS
+
+obs-day         =       [CFWS] 1*2DIGIT [CFWS]
+
+obs-hour        =       [CFWS] 2DIGIT [CFWS]
+
+obs-minute      =       [CFWS] 2DIGIT [CFWS]
+
+obs-second      =       [CFWS] 2DIGIT [CFWS]
+
+obs-zone        =       "UT" / "GMT" /          ; Universal Time
+
+
+
+Resnick                     Standards Track                    [Page 31]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+                                                ; North American UT
+                                                ; offsets
+                        "EST" / "EDT" /         ; Eastern:  - 5/ - 4
+                        "CST" / "CDT" /         ; Central:  - 6/ - 5
+                        "MST" / "MDT" /         ; Mountain: - 7/ - 6
+                        "PST" / "PDT" /         ; Pacific:  - 8/ - 7
+
+                        %d65-73 /               ; Military zones - "A"
+                        %d75-90 /               ; through "I" and "K"
+                        %d97-105 /              ; through "Z", both
+                        %d107-122               ; upper and lower case
+
+   Where a two or three digit year occurs in a date, the year is to be
+   interpreted as follows: If a two digit year is encountered whose
+   value is between 00 and 49, the year is interpreted by adding 2000,
+   ending up with a value between 2000 and 2049.  If a two digit year is
+   encountered with a value between 50 and 99, or any three digit year
+   is encountered, the year is interpreted by adding 1900.
+
+   In the obsolete time zone, "UT" and "GMT" are indications of
+   "Universal Time" and "Greenwich Mean Time" respectively and are both
+   semantically identical to "+0000".
+
+   The remaining three character zones are the US time zones.  The first
+   letter, "E", "C", "M", or "P" stands for "Eastern", "Central",
+   "Mountain" and "Pacific".  The second letter is either "S" for
+   "Standard" time, or "D" for "Daylight" (or summer) time.  Their
+   interpretations are as follows:
+
+   EDT is semantically equivalent to -0400
+   EST is semantically equivalent to -0500
+   CDT is semantically equivalent to -0500
+   CST is semantically equivalent to -0600
+   MDT is semantically equivalent to -0600
+   MST is semantically equivalent to -0700
+   PDT is semantically equivalent to -0700
+   PST is semantically equivalent to -0800
+
+   The 1 character military time zones were defined in a non-standard
+   way in [RFC822] and are therefore unpredictable in their meaning.
+   The original definitions of the military zones "A" through "I" are
+   equivalent to "+0100" through "+0900" respectively; "K", "L", and "M"
+   are equivalent to  "+1000", "+1100", and "+1200" respectively; "N"
+   through "Y" are equivalent to "-0100" through "-1200" respectively;
+   and "Z" is equivalent to "+0000".  However, because of the error in
+   [RFC822], they SHOULD all be considered equivalent to "-0000" unless
+   there is out-of-band information confirming their meaning.
+
+
+
+
+Resnick                     Standards Track                    [Page 32]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   Other multi-character (usually between 3 and 5) alphabetic time zones
+   have been used in Internet messages.  Any such time zone whose
+   meaning is not known SHOULD be considered equivalent to "-0000"
+   unless there is out-of-band information confirming their meaning.
+
+4.4. Obsolete Addressing
+
+   There are three primary differences in addressing.  First, mailbox
+   addresses were allowed to have a route portion before the addr-spec
+   when enclosed in "<" and ">".  The route is simply a comma-separated
+   list of domain names, each preceded by "@", and the list terminated
+   by a colon.  Second, CFWS were allowed between the period-separated
+   elements of local-part and domain (i.e., dot-atom was not used).  In
+   addition, local-part is allowed to contain quoted-string in addition
+   to just atom.  Finally, mailbox-list and address-list were allowed to
+   have "null" members.  That is, there could be two or more commas in
+   such a list with nothing in between them.
+
+obs-angle-addr  =       [CFWS] "<" [obs-route] addr-spec ">" [CFWS]
+
+obs-route       =       [CFWS] obs-domain-list ":" [CFWS]
+
+obs-domain-list =       "@" domain *(*(CFWS / "," ) [CFWS] "@" domain)
+
+obs-local-part  =       word *("." word)
+
+obs-domain      =       atom *("." atom)
+
+obs-mbox-list   =       1*([mailbox] [CFWS] "," [CFWS]) [mailbox]
+
+obs-addr-list   =       1*([address] [CFWS] "," [CFWS]) [address]
+
+   When interpreting addresses, the route portion SHOULD be ignored.
+
+4.5. Obsolete header fields
+
+   Syntactically, the primary difference in the obsolete field syntax is
+   that it allows multiple occurrences of any of the fields and they may
+   occur in any order.  Also, any amount of white space is allowed
+   before the ":" at the end of the field name.
+
+obs-fields      =       *(obs-return /
+                        obs-received /
+                        obs-orig-date /
+                        obs-from /
+                        obs-sender /
+                        obs-reply-to /
+                        obs-to /
+
+
+
+Resnick                     Standards Track                    [Page 33]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+                        obs-cc /
+                        obs-bcc /
+                        obs-message-id /
+                        obs-in-reply-to /
+                        obs-references /
+                        obs-subject /
+                        obs-comments /
+                        obs-keywords /
+                        obs-resent-date /
+                        obs-resent-from /
+                        obs-resent-send /
+                        obs-resent-rply /
+                        obs-resent-to /
+                        obs-resent-cc /
+                        obs-resent-bcc /
+                        obs-resent-mid /
+                        obs-optional)
+
+   Except for destination address fields (described in section 4.5.3),
+   the interpretation of multiple occurrences of fields is unspecified.
+   Also, the interpretation of trace fields and resent fields which do
+   not occur in blocks prepended to the message is unspecified as well.
+   Unless otherwise noted in the following sections, interpretation of
+   other fields is identical to the interpretation of their non-obsolete
+   counterparts in section 3.
+
+4.5.1. Obsolete origination date field
+
+obs-orig-date   =       "Date" *WSP ":" date-time CRLF
+
+4.5.2. Obsolete originator fields
+
+obs-from        =       "From" *WSP ":" mailbox-list CRLF
+
+obs-sender      =       "Sender" *WSP ":" mailbox CRLF
+
+obs-reply-to    =       "Reply-To" *WSP ":" mailbox-list CRLF
+
+4.5.3. Obsolete destination address fields
+
+obs-to          =       "To" *WSP ":" address-list CRLF
+
+obs-cc          =       "Cc" *WSP ":" address-list CRLF
+
+obs-bcc         =       "Bcc" *WSP ":" (address-list / [CFWS]) CRLF
+
+
+
+
+
+
+Resnick                     Standards Track                    [Page 34]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   When multiple occurrences of destination address fields occur in a
+   message, they SHOULD be treated as if the address-list in the first
+   occurrence of the field is combined with the address lists of the
+   subsequent occurrences by adding a comma and concatenating.
+
+4.5.4. Obsolete identification fields
+
+   The obsolete "In-Reply-To:" and "References:" fields differ from the
+   current syntax in that they allow phrase (words or quoted strings) to
+   appear.  The obsolete forms of the left and right sides of msg-id
+   allow interspersed CFWS, making them syntactically identical to
+   local-part and domain respectively.
+
+obs-message-id  =       "Message-ID" *WSP ":" msg-id CRLF
+
+obs-in-reply-to =       "In-Reply-To" *WSP ":" *(phrase / msg-id) CRLF
+
+obs-references  =       "References" *WSP ":" *(phrase / msg-id) CRLF
+
+obs-id-left     =       local-part
+
+obs-id-right    =       domain
+
+   For purposes of interpretation, the phrases in the "In-Reply-To:" and
+   "References:" fields are ignored.
+
+   Semantically, none of the optional CFWS surrounding the local-part
+   and the domain are part of the obs-id-left and obs-id-right
+   respectively.
+
+4.5.5. Obsolete informational fields
+
+obs-subject     =       "Subject" *WSP ":" unstructured CRLF
+
+obs-comments    =       "Comments" *WSP ":" unstructured CRLF
+
+obs-keywords    =       "Keywords" *WSP ":" obs-phrase-list CRLF
+
+4.5.6. Obsolete resent fields
+
+   The obsolete syntax adds a "Resent-Reply-To:" field, which consists
+   of the field name, the optional comments and folding white space, the
+   colon, and a comma separated list of addresses.
+
+obs-resent-from =       "Resent-From" *WSP ":" mailbox-list CRLF
+
+obs-resent-send =       "Resent-Sender" *WSP ":" mailbox CRLF
+
+
+
+
+Resnick                     Standards Track                    [Page 35]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+obs-resent-date =       "Resent-Date" *WSP ":" date-time CRLF
+
+obs-resent-to   =       "Resent-To" *WSP ":" address-list CRLF
+
+obs-resent-cc   =       "Resent-Cc" *WSP ":" address-list CRLF
+
+obs-resent-bcc  =       "Resent-Bcc" *WSP ":"
+                         (address-list / [CFWS]) CRLF
+
+obs-resent-mid  =       "Resent-Message-ID" *WSP ":" msg-id CRLF
+
+obs-resent-rply =       "Resent-Reply-To" *WSP ":" address-list CRLF
+
+   As with other resent fields, the "Resent-Reply-To:" field is to be
+   treated as trace information only.
+
+4.5.7. Obsolete trace fields
+
+   The obs-return and obs-received are again given here as template
+   definitions, just as return and received are in section 3.  Their
+   full syntax is given in [RFC2821].
+
+obs-return      =       "Return-Path" *WSP ":" path CRLF
+
+obs-received    =       "Received" *WSP ":" name-val-list CRLF
+
+obs-path        =       obs-angle-addr
+
+4.5.8. Obsolete optional fields
+
+obs-optional    =       field-name *WSP ":" unstructured CRLF
+
+5. Security Considerations
+
+   Care needs to be taken when displaying messages on a terminal or
+   terminal emulator.  Powerful terminals may act on escape sequences
+   and other combinations of ASCII control characters with a variety of
+   consequences.  They can remap the keyboard or permit other
+   modifications to the terminal which could lead to denial of service
+   or even damaged data.  They can trigger (sometimes programmable)
+   answerback messages which can allow a message to cause commands to be
+   issued on the recipient's behalf.  They can also effect the operation
+   of terminal attached devices such as printers.  Message viewers may
+   wish to strip potentially dangerous terminal escape sequences from
+   the message prior to display.  However, other escape sequences appear
+   in messages for useful purposes (cf. [RFC2045, RFC2046, RFC2047,
+   RFC2048, RFC2049, ISO2022]) and therefore should not be stripped
+   indiscriminately.
+
+
+
+Resnick                     Standards Track                    [Page 36]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   Transmission of non-text objects in messages raises additional
+   security issues.  These issues are discussed in [RFC2045, RFC2046,
+   RFC2047, RFC2048, RFC2049].
+
+   Many implementations use the "Bcc:" (blind carbon copy) field
+   described in section 3.6.3 to facilitate sending messages to
+   recipients without revealing the addresses of one or more of the
+   addressees to the other recipients.  Mishandling this use of "Bcc:"
+   has implications for confidential information that might be revealed,
+   which could eventually lead to security problems through knowledge of
+   even the existence of a particular mail address.  For example, if
+   using the first method described in section 3.6.3, where the "Bcc:"
+   line is removed from the message, blind recipients have no explicit
+   indication that they have been sent a blind copy, except insofar as
+   their address does not appear in the message header.  Because of
+   this, one of the blind addressees could potentially send a reply to
+   all of the shown recipients and accidentally reveal that the message
+   went to the blind recipient.  When the second method from section
+   3.6.3 is used, the blind recipient's address appears in the "Bcc:"
+   field of a separate copy of the message. If the "Bcc:" field sent
+   contains all of the blind addressees, all of the "Bcc:" recipients
+   will be seen by each "Bcc:" recipient.  Even if a separate message is
+   sent to each "Bcc:" recipient with only the individual's address,
+   implementations still need to be careful to process replies to the
+   message as per section 3.6.3 so as not to accidentally reveal the
+   blind recipient to other recipients.
+
+6. Bibliography
+
+   [ASCII]    American National Standards Institute (ANSI), Coded
+              Character Set - 7-Bit American National Standard Code for
+              Information Interchange, ANSI X3.4, 1986.
+
+   [ISO2022] International Organization for Standardization (ISO),
+              Information processing - ISO 7-bit and 8-bit coded
+              character sets - Code extension techniques, Third edition
+              - 1986-05-01, ISO 2022, 1986.
+
+   [RFC822]   Crocker, D., "Standard for the Format of ARPA Internet
+              Text Messages", RFC 822, August 1982.
+
+   [RFC2045]  Freed, N. and  N. Borenstein, "Multipurpose Internet Mail
+              Extensions (MIME) Part One: Format of Internet Message
+              Bodies", RFC 2045, November 1996.
+
+   [RFC2046]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
+              Extensions (MIME) Part Two: Media Types", RFC 2046,
+              November 1996.
+
+
+
+Resnick                     Standards Track                    [Page 37]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   [RFC2047]  Moore, K., "Multipurpose Internet Mail Extensions (MIME)
+              Part Three: Message Header Extensions for Non-ASCII Text",
+              RFC 2047, November 1996.
+
+   [RFC2048]  Freed, N., Klensin, J. and J. Postel, "Multipurpose
+              Internet Mail Extensions (MIME) Part Four: Format of
+              Internet Message Bodies", RFC 2048, November 1996.
+
+   [RFC2049]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
+              Extensions (MIME) Part Five: Conformance Criteria and
+              Examples", RFC 2049, November 1996.
+
+   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
+              Requirement Levels", BCP 14, RFC 2119, March 1997.
+
+   [RFC2234]  Crocker, D., Editor, and P. Overell, "Augmented BNF for
+              Syntax Specifications: ABNF", RFC 2234, November 1997.
+
+   [RFC2821]  Klensin, J., Editor, "Simple Mail Transfer Protocol", RFC
+              2821, March 2001.
+
+   [STD3]     Braden, R., "Host Requirements", STD 3, RFC 1122 and RFC
+              1123, October 1989.
+
+   [STD12]    Mills, D., "Network Time Protocol", STD 12, RFC 1119,
+              September 1989.
+
+   [STD13]    Mockapetris, P., "Domain Name System", STD 13, RFC 1034
+              and RFC 1035,  November 1987.
+
+   [STD14]    Partridge, C., "Mail Routing and the Domain System", STD
+              14, RFC 974, January 1986.
+
+7. Editor's Address
+
+   Peter W. Resnick
+   QUALCOMM Incorporated
+   5775 Morehouse Drive
+   San Diego, CA 92121-1714
+   USA
+
+   Phone: +1 858 651 4478
+   Fax:   +1 858 651 1102
+   EMail: presnick@qualcomm.com
+
+
+
+
+
+
+
+Resnick                     Standards Track                    [Page 38]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+8. Acknowledgements
+
+   Many people contributed to this document.  They included folks who
+   participated in the Detailed Revision and Update of Messaging
+   Standards (DRUMS) Working Group of the Internet Engineering Task
+   Force (IETF), the chair of DRUMS, the Area Directors of the IETF, and
+   people who simply sent their comments in via e-mail.  The editor is
+   deeply indebted to them all and thanks them sincerely.  The below
+   list includes everyone who sent e-mail concerning this document.
+   Hopefully, everyone who contributed is named here:
+
+   Matti Aarnio              Barry Finkel           Larry Masinter
+   Tanaka Akira              Erik Forsberg          Denis McKeon
+   Russ Allbery              Chuck Foster           William P McQuillan
+   Eric Allman               Paul Fox               Alexey Melnikov
+   Harald Tveit Alvestrand   Klaus M. Frank         Perry E. Metzger
+   Ran Atkinson              Ned Freed              Steven Miller
+   Jos Backus                Jochen Friedrich       Keith Moore
+   Bruce Balden              Randall C. Gellens     John Gardiner Myers
+   Dave Barr                 Sukvinder Singh Gill   Chris Newman
+   Alan Barrett              Tim Goodwin            John W. Noerenberg
+   John Beck                 Philip Guenther        Eric Norman
+   J. Robert von Behren      Tony Hansen            Mike O'Dell
+   Jos den Bekker            John Hawkinson         Larry Osterman
+   D. J. Bernstein           Philip Hazel           Paul Overell
+   James Berriman            Kai Henningsen         Jacob Palme
+   Norbert Bollow            Robert Herriot         Michael A. Patton
+   Raj Bose                  Paul Hethmon           Uzi Paz
+   Antony Bowesman           Jim Hill               Michael A. Quinlan
+   Scott Bradner             Paul E. Hoffman        Eric S. Raymond
+   Randy Bush                Steve Hole             Sam Roberts
+   Tom Byrer                 Kari Hurtta            Hugh Sasse
+   Bruce Campbell            Marco S. Hyman         Bart Schaefer
+   Larry Campbell            Ofer Inbar             Tom Scola
+   W. J. Carpenter           Olle Jarnefors         Wolfgang Segmuller
+   Michael Chapman           Kevin Johnson          Nick Shelness
+   Richard Clayton           Sudish Joseph          John Stanley
+   Maurizio Codogno          Maynard Kang           Einar Stefferud
+   Jim Conklin               Prabhat Keni           Jeff Stephenson
+   R. Kelley Cook            John C. Klensin        Bernard Stern
+   Steve Coya                Graham Klyne           Peter Sylvester
+   Mark Crispin              Brad Knowles           Mark Symons
+   Dave Crocker              Shuhei Kobayashi       Eric Thomas
+   Matt Curtin               Peter Koch             Lee Thompson
+   Michael D'Errico          Dan Kohn               Karel De Vriendt
+   Cyrus Daboo               Christian Kuhtz        Matthew Wall
+   Jutta Degener             Anand Kumria           Rolf Weber
+   Mark Delany               Steen Larsen           Brent B. Welch
+
+
+
+Resnick                     Standards Track                    [Page 39]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   Steve Dorner              Eliot Lear             Dan Wing
+   Harold A. Driscoll        Barry Leiba            Jack De Winter
+   Michael Elkins            Jay Levitt             Gregory J. Woodhouse
+   Robert Elz                Lars-Johan Liman       Greg A. Woods
+   Johnny Eriksson           Charles Lindsey        Kazu Yamamoto
+   Erik E. Fair              Pete Loshin            Alain Zahm
+   Roger Fajman              Simon Lyall            Jamie Zawinski
+   Patrik Faltstrom          Bill Manning           Timothy S. Zurcher
+   Claus Andre Farber        John Martin
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Resnick                     Standards Track                    [Page 40]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+Appendix A. Example messages
+
+   This section presents a selection of messages.  These are intended to
+   assist in the implementation of this standard, but should not be
+   taken as normative; that is to say, although the examples in this
+   section were carefully reviewed, if there happens to be a conflict
+   between these examples and the syntax described in sections 3 and 4
+   of this document, the syntax in those sections is to be taken as
+   correct.
+
+   Messages are delimited in this section between lines of "----".  The
+   "----" lines are not part of the message itself.
+
+A.1. Addressing examples
+
+   The following are examples of messages that might be sent between two
+   individuals.
+
+A.1.1. A message from one person to another with simple addressing
+
+   This could be called a canonical message.  It has a single author,
+   John Doe, a single recipient, Mary Smith, a subject, the date, a
+   message identifier, and a textual message in the body.
+
+----
+From: John Doe <jdoe@machine.example>
+To: Mary Smith <mary@example.net>
+Subject: Saying Hello
+Date: Fri, 21 Nov 1997 09:55:06 -0600
+Message-ID: <1234@local.machine.example>
+
+This is a message just to say hello.
+So, "Hello".
+----
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Resnick                     Standards Track                    [Page 41]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   If John's secretary Michael actually sent the message, though John
+   was the author and replies to this message should go back to him, the
+   sender field would be used:
+
+----
+From: John Doe <jdoe@machine.example>
+Sender: Michael Jones <mjones@machine.example>
+To: Mary Smith <mary@example.net>
+Subject: Saying Hello
+Date: Fri, 21 Nov 1997 09:55:06 -0600
+Message-ID: <1234@local.machine.example>
+
+This is a message just to say hello.
+So, "Hello".
+----
+
+A.1.2. Different types of mailboxes
+
+   This message includes multiple addresses in the destination fields
+   and also uses several different forms of addresses.
+
+----
+From: "Joe Q. Public" <john.q.public@example.com>
+To: Mary Smith <mary@x.test>, jdoe@example.org, Who? <one@y.test>
+Cc: <boss@nil.test>, "Giant; \"Big\" Box" <sysservices@example.net>
+Date: Tue, 1 Jul 2003 10:52:37 +0200
+Message-ID: <5678.21-Nov-1997@example.com>
+
+Hi everyone.
+----
+
+   Note that the display names for Joe Q. Public and Giant; "Big" Box
+   needed to be enclosed in double-quotes because the former contains
+   the period and the latter contains both semicolon and double-quote
+   characters (the double-quote characters appearing as quoted-pair
+   construct).  Conversely, the display name for Who? could appear
+   without them because the question mark is legal in an atom.  Notice
+   also that jdoe@example.org and boss@nil.test have no display names
+   associated with them at all, and jdoe@example.org uses the simpler
+   address form without the angle brackets.
+
+
+
+
+
+
+
+
+
+
+
+Resnick                     Standards Track                    [Page 42]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+A.1.3. Group addresses
+
+----
+From: Pete <pete@silly.example>
+To: A Group:Chris Jones <c@a.test>,joe@where.test,John <jdoe@one.test>;
+Cc: Undisclosed recipients:;
+Date: Thu, 13 Feb 1969 23:32:54 -0330
+Message-ID: <testabcd.1234@silly.example>
+
+Testing.
+----
+
+   In this message, the "To:" field has a single group recipient named A
+   Group which contains 3 addresses, and a "Cc:" field with an empty
+   group recipient named Undisclosed recipients.
+
+A.2. Reply messages
+
+   The following is a series of three messages that make up a
+   conversation thread between John and Mary.  John firsts sends a
+   message to Mary, Mary then replies to John's message, and then John
+   replies to Mary's reply message.
+
+   Note especially the "Message-ID:", "References:", and "In-Reply-To:"
+   fields in each message.
+
+----
+From: John Doe <jdoe@machine.example>
+To: Mary Smith <mary@example.net>
+Subject: Saying Hello
+Date: Fri, 21 Nov 1997 09:55:06 -0600
+Message-ID: <1234@local.machine.example>
+
+This is a message just to say hello.
+So, "Hello".
+----
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Resnick                     Standards Track                    [Page 43]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   When sending replies, the Subject field is often retained, though
+   prepended with "Re: " as described in section 3.6.5.
+
+----
+From: Mary Smith <mary@example.net>
+To: John Doe <jdoe@machine.example>
+Reply-To: "Mary Smith: Personal Account" <smith@home.example>
+Subject: Re: Saying Hello
+Date: Fri, 21 Nov 1997 10:01:10 -0600
+Message-ID: <3456@example.net>
+In-Reply-To: <1234@local.machine.example>
+References: <1234@local.machine.example>
+
+This is a reply to your hello.
+----
+
+   Note the "Reply-To:" field in the above message.  When John replies
+   to Mary's message above, the reply should go to the address in the
+   "Reply-To:" field instead of the address in the "From:" field.
+
+----
+To: "Mary Smith: Personal Account" <smith@home.example>
+From: John Doe <jdoe@machine.example>
+Subject: Re: Saying Hello
+Date: Fri, 21 Nov 1997 11:00:00 -0600
+Message-ID: <abcd.1234@local.machine.tld>
+In-Reply-To: <3456@example.net>
+References: <1234@local.machine.example> <3456@example.net>
+
+This is a reply to your reply.
+----
+
+A.3. Resent messages
+
+   Start with the message that has been used as an example several
+   times:
+
+----
+From: John Doe <jdoe@machine.example>
+To: Mary Smith <mary@example.net>
+Subject: Saying Hello
+Date: Fri, 21 Nov 1997 09:55:06 -0600
+Message-ID: <1234@local.machine.example>
+
+This is a message just to say hello.
+So, "Hello".
+----
+
+
+
+
+Resnick                     Standards Track                    [Page 44]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   Say that Mary, upon receiving this message, wishes to send a copy of
+   the message to Jane such that (a) the message would appear to have
+   come straight from John; (b) if Jane replies to the message, the
+   reply should go back to John; and (c) all of the original
+   information, like the date the message was originally sent to Mary,
+   the message identifier, and the original addressee, is preserved.  In
+   this case, resent fields are prepended to the message:
+
+----
+Resent-From: Mary Smith <mary@example.net>
+Resent-To: Jane Brown <j-brown@other.example>
+Resent-Date: Mon, 24 Nov 1997 14:22:01 -0800
+Resent-Message-ID: <78910@example.net>
+From: John Doe <jdoe@machine.example>
+To: Mary Smith <mary@example.net>
+Subject: Saying Hello
+Date: Fri, 21 Nov 1997 09:55:06 -0600
+Message-ID: <1234@local.machine.example>
+
+This is a message just to say hello.
+So, "Hello".
+----
+
+   If Jane, in turn, wished to resend this message to another person,
+   she would prepend her own set of resent header fields to the above
+   and send that.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Resnick                     Standards Track                    [Page 45]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+A.4. Messages with trace fields
+
+   As messages are sent through the transport system as described in
+   [RFC2821], trace fields are prepended to the message.  The following
+   is an example of what those trace fields might look like.  Note that
+   there is some folding white space in the first one since these lines
+   can be long.
+
+----
+Received: from x.y.test
+   by example.net
+   via TCP
+   with ESMTP
+   id ABC12345
+   for <mary@example.net>;  21 Nov 1997 10:05:43 -0600
+Received: from machine.example by x.y.test; 21 Nov 1997 10:01:22 -0600
+From: John Doe <jdoe@machine.example>
+To: Mary Smith <mary@example.net>
+Subject: Saying Hello
+Date: Fri, 21 Nov 1997 09:55:06 -0600
+Message-ID: <1234@local.machine.example>
+
+This is a message just to say hello.
+So, "Hello".
+----
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Resnick                     Standards Track                    [Page 46]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+A.5. White space, comments, and other oddities
+
+   White space, including folding white space, and comments can be
+   inserted between many of the tokens of fields.  Taking the example
+   from A.1.3, white space and comments can be inserted into all of the
+   fields.
+
+----
+From: Pete(A wonderful \) chap) <pete(his account)@silly.test(his host)>
+To:A Group(Some people)
+     :Chris Jones <c@(Chris's host.)public.example>,
+         joe@example.org,
+  John <jdoe@one.test> (my dear friend); (the end of the group)
+Cc:(Empty list)(start)Undisclosed recipients  :(nobody(that I know))  ;
+Date: Thu,
+      13
+        Feb
+          1969
+      23:32
+               -0330 (Newfoundland Time)
+Message-ID:              <testabcd.1234@silly.test>
+
+Testing.
+----
+
+   The above example is aesthetically displeasing, but perfectly legal.
+   Note particularly (1) the comments in the "From:" field (including
+   one that has a ")" character appearing as part of a quoted-pair); (2)
+   the white space absent after the ":" in the "To:" field as well as
+   the comment and folding white space after the group name, the special
+   character (".") in the comment in Chris Jones's address, and the
+   folding white space before and after "joe@example.org,"; (3) the
+   multiple and nested comments in the "Cc:" field as well as the
+   comment immediately following the ":" after "Cc"; (4) the folding
+   white space (but no comments except at the end) and the missing
+   seconds in the time of the date field; and (5) the white space before
+   (but not within) the identifier in the "Message-ID:" field.
+
+A.6. Obsoleted forms
+
+   The following are examples of obsolete (that is, the "MUST NOT
+   generate") syntactic elements described in section 4 of this
+   document.
+
+
+
+
+
+
+
+
+Resnick                     Standards Track                    [Page 47]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+A.6.1. Obsolete addressing
+
+   Note in the below example the lack of quotes around Joe Q. Public,
+   the route that appears in the address for Mary Smith, the two commas
+   that appear in the "To:" field, and the spaces that appear around the
+   "." in the jdoe address.
+
+----
+From: Joe Q. Public <john.q.public@example.com>
+To: Mary Smith <@machine.tld:mary@example.net>, , jdoe@test   . example
+Date: Tue, 1 Jul 2003 10:52:37 +0200
+Message-ID: <5678.21-Nov-1997@example.com>
+
+Hi everyone.
+----
+
+A.6.2. Obsolete dates
+
+   The following message uses an obsolete date format, including a non-
+   numeric time zone and a two digit year.  Note that although the
+   day-of-week is missing, that is not specific to the obsolete syntax;
+   it is optional in the current syntax as well.
+
+----
+From: John Doe <jdoe@machine.example>
+To: Mary Smith <mary@example.net>
+Subject: Saying Hello
+Date: 21 Nov 97 09:55:06 GMT
+Message-ID: <1234@local.machine.example>
+
+This is a message just to say hello.
+So, "Hello".
+----
+
+A.6.3. Obsolete white space and comments
+
+   White space and comments can appear between many more elements than
+   in the current syntax.  Also, folding lines that are made up entirely
+   of white space are legal.
+
+
+
+
+
+
+
+
+
+
+
+
+Resnick                     Standards Track                    [Page 48]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+----
+From  : John Doe <jdoe@machine(comment).  example>
+To    : Mary Smith
+__
+          <mary@example.net>
+Subject     : Saying Hello
+Date  : Fri, 21 Nov 1997 09(comment):   55  :  06 -0600
+Message-ID  : <1234   @   local(blah)  .machine .example>
+
+This is a message just to say hello.
+So, "Hello".
+----
+
+   Note especially the second line of the "To:" field.  It starts with
+   two space characters.  (Note that "__" represent blank spaces.)
+   Therefore, it is considered part of the folding as described in
+   section 4.2.  Also, the comments and white space throughout
+   addresses, dates, and message identifiers are all part of the
+   obsolete syntax.
+
+Appendix B. Differences from earlier standards
+
+   This appendix contains a list of changes that have been made in the
+   Internet Message Format from earlier standards, specifically [RFC822]
+   and [STD3].  Items marked with an asterisk (*) below are items which
+   appear in section 4 of this document and therefore can no longer be
+   generated.
+
+   1. Period allowed in obsolete form of phrase.
+   2. ABNF moved out of document to [RFC2234].
+   3. Four or more digits allowed for year.
+   4. Header field ordering (and lack thereof) made explicit.
+   5. Encrypted header field removed.
+   6. Received syntax loosened to allow any token/value pair.
+   7. Specifically allow and give meaning to "-0000" time zone.
+   8. Folding white space is not allowed between every token.
+   9. Requirement for destinations removed.
+   10. Forwarding and resending redefined.
+   11. Extension header fields no longer specifically called out.
+   12. ASCII 0 (null) removed.*
+   13. Folding continuation lines cannot contain only white space.*
+   14. Free insertion of comments not allowed in date.*
+   15. Non-numeric time zones not allowed.*
+   16. Two digit years not allowed.*
+   17. Three digit years interpreted, but not allowed for generation.
+   18. Routes in addresses not allowed.*
+   19. CFWS within local-parts and domains not allowed.*
+   20. Empty members of address lists not allowed.*
+
+
+
+Resnick                     Standards Track                    [Page 49]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+   21. Folding white space between field name and colon not allowed.*
+   22. Comments between field name and colon not allowed.
+   23. Tightened syntax of in-reply-to and references.*
+   24. CFWS within msg-id not allowed.*
+   25. Tightened semantics of resent fields as informational only.
+   26. Resent-Reply-To not allowed.*
+   27. No multiple occurrences of fields (except resent and received).*
+   28. Free CR and LF not allowed.*
+   29. Routes in return path not allowed.*
+   30. Line length limits specified.
+   31. Bcc more clearly specified.
+
+Appendix C. Notices
+
+   Intellectual Property
+
+   The IETF takes no position regarding the validity or scope of any
+   intellectual property 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; neither does it represent that it
+   has made any effort to identify any such rights.  Information on the
+   IETF's procedures with respect to rights in standards-track and
+   standards-related documentation can be found in BCP-11.  Copies of
+   claims of rights made available for publication 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 implementors or users of this specification can
+   be obtained from the IETF Secretariat.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Resnick                     Standards Track                    [Page 50]
+
+RFC 2822                Internet Message Format               April 2001
+
+
+Full Copyright Statement
+
+   Copyright (C) The Internet Society (2001).  All Rights Reserved.
+
+   This document and translations of it may be copied and furnished to
+   others, and derivative works that comment on or otherwise explain it
+   or assist in its implementation may be prepared, copied, published
+   and distributed, in whole or in part, without restriction of any
+   kind, provided that the above copyright notice and this paragraph are
+   included on all such copies and derivative works.  However, this
+   document itself may not be modified in any way, such as by removing
+   the copyright notice or references to the Internet Society or other
+   Internet organizations, except as needed for the purpose of
+   developing Internet standards in which case the procedures for
+   copyrights defined in the Internet Standards process must be
+   followed, or as required to translate it into languages other than
+   English.
+
+   The limited permissions granted above are perpetual and will not be
+   revoked by the Internet Society or its successors or assigns.
+
+   This document and the information contained herein is provided on an
+   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
+   TASK FORCE DISCLAIMS 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.
+
+Acknowledgement
+
+   Funding for the RFC Editor function is currently provided by the
+   Internet Society.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Resnick                     Standards Track                    [Page 51]
+