Registration of Mail and MIME Header Fields
RFC 4021

Document Type RFC - Proposed Standard (March 2005; No errata)
Updated by RFC 5322
Was draft-klyne-hdrreg-mail (individual in app area)
Last updated 2013-03-02
Stream IETF
Formats plain text pdf html
Stream WG state (None)
Consensus Unknown
Document shepherd No shepherd assigned
IESG IESG state RFC 4021 (Proposed Standard)
Telechat date
Responsible AD Ted Hardie
Send notices to (None)
Network Working Group                                           G. Klyne
Request for Comments: 4021                          University of Oxford
Category: Standards Track                                       J. Palme
                                                 Stockholm University/KT
                                                              March 2005

              Registration of Mail and MIME Header Fields

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This document defines the initial IANA registration for permanent
   mail and MIME message header fields, per RFC 3864.

Table of Contents
   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
       1.1.  Structure of This Document . . . . . . . . . . . . . . .  3
       1.2.  Document Terminology and Conventions . . . . . . . . . .  4
   2.  Registration Templates . . . . . . . . . . . . . . . . . . . .  4
       2.1.  Permanent Mail Header Field Registrations  . . . . . . .  4
             2.1.1.  Header Field: Date . . . . . . . . . . . . . . .  6
             2.1.2.  Header Field: From . . . . . . . . . . . . . . .  7
             2.1.3.  Header Field: Sender . . . . . . . . . . . . . .  7
             2.1.4.  Header Field: Reply-To . . . . . . . . . . . . .  8
             2.1.5.  Header Field: To . . . . . . . . . . . . . . . .  8
             2.1.6.  Header Field: Cc . . . . . . . . . . . . . . . .  9
             2.1.7.  Header Field: Bcc  . . . . . . . . . . . . . . .  9
             2.1.8.  Header Field: Message-ID . . . . . . . . . . . . 10
             2.1.9.  Header Field: In-Reply-To  . . . . . . . . . . . 10
             2.1.10. Header Field: References . . . . . . . . . . . . 11
             2.1.11. Header Field: Subject  . . . . . . . . . . . . . 11
             2.1.12. Header Field: Comments . . . . . . . . . . . . . 12
             2.1.13. Header Field: Keywords . . . . . . . . . . . . . 12
             2.1.14. Header Field: Resent-Date  . . . . . . . . . . . 13
             2.1.15. Header Field: Resent-From  . . . . . . . . . . . 13
             2.1.16. Header Field: Resent-Sender  . . . . . . . . . . 14

G. Klyne, et al.            Standards Track                     [Page 1]
RFC 4021              Mail and MIME Header Fields             March 2005

             2.1.17. Header Field: Resent-To  . . . . . . . . . . . . 14
             2.1.18. Header Field: Resent-Cc  . . . . . . . . . . . . 15
             2.1.19. Header Field: Resent-Bcc . . . . . . . . . . . . 15
             2.1.20. Header Field: Resent-Reply-To  . . . . . . . . . 16
             2.1.21. Header Field: Resent-Message-ID  . . . . . . . . 16
             2.1.22. Header Field: Return-Path  . . . . . . . . . . . 17
             2.1.23. Header Field: Received . . . . . . . . . . . . . 17
             2.1.24. Header Field: Encrypted  . . . . . . . . . . . . 18
             2.1.25. Header Field: Disposition-Notification-To  . . . 18
             2.1.26. Header Field: Disposition-Notification-Options . 19
             2.1.27. Header Field: Accept-Language  . . . . . . . . . 19
             2.1.28. Header Field: Original-Message-ID  . . . . . . . 20
             2.1.29. Header Field: PICS-Label . . . . . . . . . . . . 20
             2.1.30. Header Field: Encoding . . . . . . . . . . . . . 21
             2.1.31. Header Field: List-Archive . . . . . . . . . . . 21
             2.1.32. Header Field: List-Help  . . . . . . . . . . . . 22
             2.1.33. Header Field: List-ID  . . . . . . . . . . . . . 22
             2.1.34. Header Field: List-Owner . . . . . . . . . . . . 23
             2.1.35. Header Field: List-Post  . . . . . . . . . . . . 23
             2.1.36. Header Field: List-Subscribe . . . . . . . . . . 24
             2.1.37. Header Field: List-Unsubscribe . . . . . . . . . 24
             2.1.38. Header Field: Message-Context  . . . . . . . . . 25
             2.1.39. Header Field: DL-Expansion-History . . . . . . . 25
             2.1.40. Header Field: Alternate-Recipient  . . . . . . . 26
             2.1.41. Header Field: Original-Encoded-Information-Types 26
             2.1.42. Header Field: Content-Return . . . . . . . . . . 27
             2.1.43. Header Field: Generate-Delivery-Report . . . . . 27
             2.1.44. Header Field: Prevent-NonDelivery-Report . . . . 28
             2.1.45. Header Field: Obsoletes  . . . . . . . . . . . . 28
             2.1.46. Header Field: Supersedes . . . . . . . . . . . . 29
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