Common Internet Message Headers
RFC 2076

Document Type RFC - Informational (February 1997; Errata)
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Network Working Group                                          J. Palme
Request for Comments: 2076                     Stockholm University/KTH
Category: Informational                                   February 1997

                    Common Internet Message Headers

Status of this Memo

   This memo provides information for the Internet community.  This memo
   does not specify an Internet standard of any kind.  Distribution of
   this memo is unlimited.

Abstract

   This memo contains a table of commonly occurring headers in headings
   of e-mail messages. The document compiles information from other RFCs
   such as RFC 822, RFC 1036, RFC 1123, RFC 1327, RFC 1496, RFC 1521,
   RFC 1766, RFC 1806, RFC 1864 and RFC 1911. A few commonly occurring
   headers which are not defined in RFCs are also included. For each
   header, the memo gives a short description and a reference to the RFC
   in which the header is defined.

Table of contents
   1. Introduction..............................................  2
   2. Use of gatewaying headers.................................  3
   3. Table of headers..........................................  3
        3.1 Phrases used in the tables..........................  3
        3.2 Trace information...................................  5
        3.3 Format and control information......................  5
        3.4 Sender and recipient indication.....................  6
        3.5 Response control....................................  9
        3.6 Message identification and referral headers......... 11
        3.7 Other textual headers............................... 12
        3.8 Headers containing dates and times.................. 13
        3.9 Quality information................................. 13
        3.10 Language information............................... 14
        3.11 Size information................................... 14
        3.12 Conversion control................................. 15
        3.13 Encoding information............................... 15
        3.14 Resent-headers..................................... 16
        3.15 Security and reliability........................... 16
        3.16 Miscellaneous...................................... 16
   4. Acknowledgments........................................... 18

Palme                        Informational                      [Page 1]
RFC 2076                Internet Message Headers           February 1997

   5. References................................................ 18
   6. Author's Address.......................................... 20
   Appendix A:
   Headers sorted by Internet RFC document in which they appear. 21
   Appendix B:
   Alphabetical index........................................... 25

1. Introduction

   Many different Internet standards and RFCs define headers which may
   occur on Internet Mail Messages and Usenet News Articles. The
   intention of this document is to list all such headers in one
   document as an aid to people developing message systems or interested
   in Internet Mail standards.

   The document contains all headers which the author has found in the
   following Internet standards: , RFC 822 [2], RFC 1036 [3], RFC 1123
   [5], RFC 1327 [7], RFC 1496 [8], RFC 1521 [11], RFC 1766 [12], RFC
   1806 [14], RFC 1864[17] and RFC 1911[20]. Note in particular that
   heading attributes defined in PEM (RFC 1421-1424) and MOSS (RFC 1848
   [16]) are not included. PEM and MOSS headers only appear inside the
   body of a message, and thus are not headers in the RFC 822 sense.
   Mail attributes in envelopes, i.e. attributes controlling the message
   transport mechanism between mail and news servers, are not included.
   This means that attributes from SMTP [1], UUCP [18] and NNTP [15] are
   mainly not covered either. Headings used only in HTTP [19] are not
   included yet, but may be included in future version of this memo. A
   few additional headers which often can be found in e-mail headings
   but are not part of any Internet standard are also included.

   For each header, the document gives a short description and a
   reference to the Internet standard or RFC, in which they are defined.

   The header names given here are spelled the same way as when they are
   actually used. This is usually American but sometimes English
   spelling.  One header in particular, "Organisation/Organization",
   occurs in e-mail headers sometimes with the English and other times
   with the American spelling.

   The following words are used in this memo with the meaning specified
   below:

   heading           Formatted text at the top of a message, ended by a
                     blank line

   header = heading  One field in the heading, beginning with a field
   field             name, colon, and followed by the field value(s)

Palme                        Informational                      [Page 2]
RFC 2076                Internet Message Headers           February 1997
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