tech-invite   World Map     

IETF     RFCs     Groups     SIP     ABNFs    |    3GPP     Specs     Glossaries     Architecture     IMS     UICC    |    search

RFC 4021

Proposed STD
Pages: 54
Top     in Index     Prev     Next
in Group Index     Prev in Group     Next in Group     Group: ~mail

Registration of Mail and MIME Header Fields

Part 1 of 2, p. 1 to 25
None       Next RFC Part

Updated by:    5322


Top       ToC       Page 1 
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

Top      ToC       Page 2 
             2.1.17. Header Field: Resent-To  . . . . . . . . . . . . 14
             2.1.18. Header Field: Resent-Cc  . . . . . . . . . . . . 15
             2.1.19. Header Field: Resent-Bcc . . . . . . . . . . . . 15
             2.1.20. Header Field: Resent-Reply-To  . . . . . . . . . 16
             2.1.21. Header Field: Resent-Message-ID  . . . . . . . . 16
             2.1.22. Header Field: Return-Path  . . . . . . . . . . . 17
             2.1.23. Header Field: Received . . . . . . . . . . . . . 17
             2.1.24. Header Field: Encrypted  . . . . . . . . . . . . 18
             2.1.25. Header Field: Disposition-Notification-To  . . . 18
             2.1.26. Header Field: Disposition-Notification-Options . 19
             2.1.27. Header Field: Accept-Language  . . . . . . . . . 19
             2.1.28. Header Field: Original-Message-ID  . . . . . . . 20
             2.1.29. Header Field: PICS-Label . . . . . . . . . . . . 20
             2.1.30. Header Field: Encoding . . . . . . . . . . . . . 21
             2.1.31. Header Field: List-Archive . . . . . . . . . . . 21
             2.1.32. Header Field: List-Help  . . . . . . . . . . . . 22
             2.1.33. Header Field: List-ID  . . . . . . . . . . . . . 22
             2.1.34. Header Field: List-Owner . . . . . . . . . . . . 23
             2.1.35. Header Field: List-Post  . . . . . . . . . . . . 23
             2.1.36. Header Field: List-Subscribe . . . . . . . . . . 24
             2.1.37. Header Field: List-Unsubscribe . . . . . . . . . 24
             2.1.38. Header Field: Message-Context  . . . . . . . . . 25
             2.1.39. Header Field: DL-Expansion-History . . . . . . . 25
             2.1.40. Header Field: Alternate-Recipient  . . . . . . . 26
             2.1.41. Header Field: Original-Encoded-Information-Types 26
             2.1.42. Header Field: Content-Return . . . . . . . . . . 27
             2.1.43. Header Field: Generate-Delivery-Report . . . . . 27
             2.1.44. Header Field: Prevent-NonDelivery-Report . . . . 28
             2.1.45. Header Field: Obsoletes  . . . . . . . . . . . . 28
             2.1.46. Header Field: Supersedes . . . . . . . . . . . . 29
             2.1.47. Header Field: Content-Identifier . . . . . . . . 29
             2.1.48. Header Field: Delivery-Date  . . . . . . . . . . 30
             2.1.49. Header Field: Expiry-Date  . . . . . . . . . . . 30
             2.1.50. Header Field: Expires  . . . . . . . . . . . . . 31
             2.1.51. Header Field: Reply-By . . . . . . . . . . . . . 31
             2.1.52. Header Field: Importance . . . . . . . . . . . . 32
             2.1.53. Header Field: Incomplete-Copy  . . . . . . . . . 32
             2.1.54. Header Field: Priority . . . . . . . . . . . . . 33
             2.1.55. Header Field: Sensitivity  . . . . . . . . . . . 33
             2.1.56. Header Field: Language . . . . . . . . . . . . . 34
             2.1.57. Header Field: Conversion . . . . . . . . . . . . 34
             2.1.58. Header Field: Conversion-With-Loss . . . . . . . 35
             2.1.59. Header Field: Message-Type . . . . . . . . . . . 35
             2.1.60. Header Field: Autosubmitted  . . . . . . . . . . 36
             2.1.61. Header Field: Autoforwarded  . . . . . . . . . . 36
             2.1.62. Header Field: Discarded-X400-IPMS-Extensions . . 37
             2.1.63. Header Field: Discarded-X400-MTS-Extensions  . . 37
             2.1.64. Header Field: Disclose-Recipients  . . . . . . . 38

Top      ToC       Page 3 
             2.1.65. Header Field: Deferred-Delivery  . . . . . . . . 38
             2.1.66. Header Field: Latest-Delivery-Time . . . . . . . 39
             2.1.67. Header Field: Originator-Return-Address  . . . . 39
             2.1.68. Header Field: X400-Content-Identifier  . . . . . 40
             2.1.69. Header Field: X400-Content-Return  . . . . . . . 40
             2.1.70. Header Field: X400-Content-Type  . . . . . . . . 41
             2.1.71. Header Field: X400-MTS-Identifier  . . . . . . . 41
             2.1.72. Header Field: X400-Originator  . . . . . . . . . 42
             2.1.73. Header Field: X400-Received  . . . . . . . . . . 42
             2.1.74. Header Field: X400-Recipients  . . . . . . . . . 43
             2.1.75. Header Field: X400-Trace . . . . . . . . . . . . 43
       2.2.  Permanent MIME Header Field Registrations  . . . . . . . 44
             2.2.1.  Header Field: MIME-Version . . . . . . . . . . . 44
             2.2.2.  Header Field: Content-ID . . . . . . . . . . . . 45
             2.2.3.  Header Field: Content-Description  . . . . . . . 45
             2.2.4.  Header Field: Content-Transfer-Encoding  . . . . 46
             2.2.5.  Header Field: Content-Type . . . . . . . . . . . 46
             2.2.6.  Header Field: Content-Base . . . . . . . . . . . 47
             2.2.7.  Header Field: Content-Location . . . . . . . . . 47
             2.2.8.  Header Field: Content-features . . . . . . . . . 48
             2.2.9.  Header Field: Content-Disposition  . . . . . . . 48
             2.2.10. Header Field: Content-Language . . . . . . . . . 49
             2.2.11. Header Field: Content-Alternative  . . . . . . . 49
             2.2.12. Header Field: Content-MD5  . . . . . . . . . . . 50
             2.2.13. Header Field: Content-Duration . . . . . . . . . 50
   3.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 50
   4.  Security Considerations  . . . . . . . . . . . . . . . . . . . 51
   5.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 51
   6.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 51
       6.1.  Normative References . . . . . . . . . . . . . . . . . . 51
       6.2.  Informative References . . . . . . . . . . . . . . . . . 53
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 53
   Full Copyright Statement . . . . . . . . . . . . . . . . . . . . . 54

1.  Introduction

   This document defines IANA registration for a number of mail message
   and MIME header fields, per registration procedures for message
   header fields [1].

   The main body of this document is automatically generated from RDF/N3
   data.  Some experimental HTML registry pages have been prepared from
   the same data and can be found at [27].

1.1.  Structure of This Document

   Section 2.1 contains the templates for initial registration of mail
   message header fields.

Top      ToC       Page 4 
   Section 2.2 contains templates for initial registration of MIME
   header fields.

1.2.  Document Terminology and Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in BCP 14, RFC 2119 [9].

2.  Registration Templates

   Header field registry entries are summarized in tabular form for
   convenience of reference and presented in full in the following
   sections.

2.1.  Permanent Mail Header Field Registrations


   Header name         Protocol
   -----------         --------
   Date                Mail      Message date and time
   From                Mail      Mailbox of message author
   Sender              Mail      Mailbox of message sender
   Reply-To            Mail      Mailbox for replies to message
   To                  Mail      Primary recipient mailbox
   Cc                  Mail      Carbon-copy recipient mailbox
   Bcc                 Mail      Blind-carbon-copy recipient
                                 mailbox
   Message-ID          Mail      Message identifier
   In-Reply-To         Mail      Identify replied-to message(s)
   References          Mail      Related message identifier(s)
   Subject             Mail      Topic of message
   Comments            Mail      Additional comments about the
                                 message
   Keywords            Mail      Message key words and/or phrases
   Resent-Date         Mail      Date and time message is resent
   Resent-From         Mail      Mailbox of person for whom message
                                 is resent
   Resent-Sender       Mail      Mailbox of person who actually
                                 resends the message
   Resent-To           Mail      Mailbox to which message is resent
   Resent-Cc           Mail      Mailbox(es) to which message is
                                 cc'ed on resend
   Resent-Bcc          Mail      Mailbox(es) to which message is
                                 bcc'ed on resend
   Resent-Reply-To     Mail      Resent reply-to
   Resent-Message-ID   Mail      Message identifier for resent
                                 message

Top      ToC       Page 5 
   Return-Path         Mail      Message return path
   Received            Mail      Mail transfer trace information
   Encrypted           Mail      Message encryption information
   Disposition-Notification-To
                       Mail      Mailbox for sending disposition
                                 notification
   Disposition-Notification-Options
                       Mail      Disposition notification options
   Accept-Language     Mail      Language(s) for auto-responses
   Original-Message-ID Mail      Original message identifier
   PICS-Label          Mail      PICS rating label
   Encoding            Mail      Message encoding and other
                                 information
   List-Archive        Mail      URL of mailing list archive
   List-Help           Mail      URL for mailing list information
   List-ID             Mail      Mailing list identifier
   List-Owner          Mail      URL for mailing list owner's
                                 mailbox
   List-Post           Mail      URL for mailing list posting
   List-Subscribe      Mail      URL for mailing list subscription
   List-Unsubscribe    Mail      URL for mailing list
                                 unsubscription
   Message-Context     Mail      Type or context of message
   DL-Expansion-History
                       Mail      Trace of distribution lists passed
   Alternate-Recipient Mail      Controls forwarding to alternate
                                 recipients
   Original-Encoded-Information-Types
                       Mail      Body part types in message
   Content-Return      Mail      Return content on non-delivery?
   Generate-Delivery-Report
                       Mail      Request delivery report generation
   Prevent-NonDelivery-Report
                       Mail      Non-delivery report required?
   Obsoletes           Mail      Reference message to be replaced
   Supersedes          Mail      Reference message to be replaced
   Content-Identifier  Mail      Message content identifier
   Delivery-Date       Mail      Message delivery time
   Expiry-Date         Mail      Message expiry time
   Expires             Mail      Message expiry time
   Reply-By            Mail      Time by which a reply is requested
   Importance          Mail      Message importance
   Incomplete-Copy     Mail      Body parts are missing
   Priority            Mail      Message priority
   Sensitivity         Mail      Message content sensitivity
   Language            Mail      X.400 message content language
   Conversion          Mail      Conversion allowed?

Top      ToC       Page 6 
   Conversion-With-Loss
                       Mail      Lossy conversion allowed?
   Message-Type        Mail      Message type: delivery report?
   Autosubmitted       Mail      Automatically submitted indicator
   Autoforwarded       Mail      Automatically forwarded indicator
   Discarded-X400-IPMS-Extensions
                       Mail      X.400 IPM extensions discarded
   Discarded-X400-MTS-Extensions
                       Mail      X.400 MTS extensions discarded
   Disclose-Recipients Mail      Disclose names of other
                                 recipients?
   Deferred-Delivery   Mail      Deferred delivery information
   Latest-Delivery-Time
                       Mail      Latest delivery time requested
   Originator-Return-Address
                       Mail      Originator return address
   X400-Content-Identifier
                       Mail      Message content identifier
   X400-Content-Return Mail      Return content on non-delivery?
   X400-Content-Type   Mail      X400 content type
   X400-MTS-Identifier Mail      X400 MTS-Identifier
   X400-Originator     Mail      X400 Originator
   X400-Received       Mail      X400 Received
   X400-Recipients     Mail      X400 Recipients
   X400-Trace          Mail      X400 Trace

2.1.1.  Header Field: Date

   Description:
      Message date and time

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.1)

   Related information:
      Specifies the date and time at which the creator of the message
      indicated that the message was complete and ready to enter the
      mail delivery system.  Defined as standard by RFC 822.

Top      ToC       Page 7 
2.1.2.  Header Field: From

   Description:
      Mailbox of message author

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.2)

   Related information:
      Specifies the author(s) of the message; that is, the mailbox(es)
      of the person(s) or system(s) responsible for the writing of the
      message.  Defined as standard by RFC 822.

2.1.3.  Header Field: Sender

   Description:
      Mailbox of message sender

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.2)

   Related information:
      Specifies the mailbox of the agent responsible for the actual
      transmission of the message.  Defined as standard by RFC 822.

Top      ToC       Page 8 
2.1.4.  Header Field: Reply-To

   Description:
      Mailbox for replies to message

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org) Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.2)

   Related information:
      When the "Reply-To:" field is present, it indicates the
      mailbox(es) to which the author of the message suggests that
      replies be sent.  Defined as standard by RFC 822.

2.1.5.  Header Field: To

   Description:
      Primary recipient mailbox

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.3)

   Related information:
      Contains the address(es) of the primary recipient(s) of the
      message.  Defined as standard by RFC 822.

Top      ToC       Page 9 
2.1.6.  Header Field: Cc

   Description:
      Carbon-copy recipient mailbox

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.3)

   Related information:
      Contains the addresses of others who are to receive the message,
      though the content of the message may not be directed at them.
      Defined as standard by RFC 822.

2.1.7.  Header Field: Bcc

   Description:
      Blind-carbon-copy recipient mailbox

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.3)

   Related information:
      Contains addresses of recipients of the message whose addresses
      are not to be revealed to other recipients of the message.
      Defined as standard by RFC 822.

Top      ToC       Page 10 
2.1.8.  Header Field: Message-ID

   Description:
      Message identifier

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.4)

   Related information:
      Contains a single unique message identifier that refers to a
      particular version of a particular message.  If the message is
      resent without changes, the original Message-ID is retained.
      Defined as standard by RFC 822.

2.1.9.  Header Field: In-Reply-To

   Description:
      Identify replied-to message(s)

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.4)

   Related information:
      The message identifier(s) of the original message(s) to which the
      current message is a reply.  Defined as standard by RFC 822.

Top      ToC       Page 11 
2.1.10.  Header Field: References

   Description:
      Related message identifier(s)

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.4)

   Related information:
      The message identifier(s) of other message(s) to which the current
      message may be related.  In RFC 2822, the definition was changed
      to say that this header field contains a list of all Message-IDs
      of messages in the preceding reply chain.  Defined as standard by
      RFC 822.

2.1.11.  Header Field: Subject

   Description:
      Topic of message

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.5)

   Related information:
      Contains a short string identifying the topic of the message.
      Defined as standard by RFC 822.

Top      ToC       Page 12 
2.1.12.  Header Field: Comments

   Description:
      Additional comments about the message

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.5)

   Related information:
      Contains any additional comments on the text of the body of the
      message.  Warning: Some mailers will not show this field to
      recipients.  Defined as standard by RFC 822.

2.1.13.  Header Field: Keywords

   Description:
      Message key words and/or phrases

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.5)

   Related information:
      Contains a comma-separated list of important words and phrases
      that might be useful for the recipient.  Defined as standard by
      RFC 822.

Top      ToC       Page 13 
2.1.14.  Header Field: Resent-Date

   Description:
      Date and time message is resent

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.6)

   Related information:
      Contains the date and time that a message is reintroduced into the
      message transfer system.  Defined as standard by RFC 822.

2.1.15.  Header Field: Resent-From

   Description:
      Mailbox of person for whom message is resent

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.6)

   Related information:
      Contains the mailbox of the agent who has reintroduced the message
      into the message transfer system, or on whose behalf the message
      has been resent.  Defined as standard by RFC 822.

Top      ToC       Page 14 
2.1.16.  Header Field: Resent-Sender

   Description:
      Mailbox of person who actually resends the message

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.6)

   Related information:
      Contains the mailbox of the agent who has reintroduced the message
      into the message transfer system, if this is different from the
      Resent-From value.  Defined as standard by RFC 822.

2.1.17.  Header Field: Resent-To

   Description:
      Mailbox to which message is resent

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.6)

   Related information:
      Contains the mailbox(es) to which the message has been resent.
      Defined as standard by RFC 822.

Top      ToC       Page 15 
2.1.18.  Header Field: Resent-Cc

   Description:
      Mailbox(es) to which message is cc'ed on resend

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.6)

   Related information:
      Contains the mailbox(es) to which message is cc'ed on resend.
      Defined as standard by RFC 822.

2.1.19.  Header Field: Resent-Bcc

   Description:
         Mailbox(es) to which message is bcc'ed on resend

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.6)

   Related information:
      Contains the mailbox(es) to which message is bcc'ed on resend.
      Defined as standard by RFC 822.

Top      ToC       Page 16 
2.1.20.  Header Field: Resent-Reply-To

   Description:
      Resent reply-to

   Applicable protocol: Mail [18]

   Status: obsolete

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18]

   Related information:
      Resent Reply-to.  Defined by RFC 822, obsoleted by RFC 2822.

2.1.21.  Header Field: Resent-Message-ID

   Description:
      Message identifier for resent message

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.6)

   Related information:
      Contains a message identifier for a resent message.  Defined as
      standard by RFC 822.

Top      ToC       Page 17 
2.1.22.  Header Field: Return-Path

   Description:
      Message return path

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.7)

   Related information:
      Return path for message response diagnostics.  See also RFC 2821
      [17].  Defined as standard by RFC 822.

2.1.23.  Header Field: Received

   Description:
      Mail transfer trace information

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2822 [18] (section 3.6.7)

   Related information:
      Contains information about receipt of the current message by a
      mail transfer agent on the transfer path.  See also RFC 2821 [17].
      Defined as standard by RFC 822.

Top      ToC       Page 18 
2.1.24.  Header Field: Encrypted

   Description:
      Message encryption information

   Applicable protocol: Mail [18]

   Status: obsolete

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 822 [2]

   Related information:
      Defined by RFC 822, but was found to be inadequately specified,
      was not widely implemented, and was removed in RFC 2822.  Current
      practice is to use separate encryption, such as S/MIME or OpenPGP,
      possibly in conjunction with RFC 1847 MIME security multiparts.

2.1.25.  Header Field: Disposition-Notification-To

   Description:
      Mailbox for sending disposition notification

   Applicable protocol: Mail [18]

   Status: standards-track

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2298 [12]

   Related information:
      Indicates that the sender wants a disposition notification when
      this message is received (read, processed, etc.) by its
      recipients.

Top      ToC       Page 19 
2.1.26.  Header Field: Disposition-Notification-Options

   Description:
      Disposition notification options

   Applicable protocol: Mail [18]

   Status: standards-track

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2298 [12]

   Related information:
      For optional modifiers on disposition notification requests.

2.1.27.  Header Field: Accept-Language

   Description:
      Language(s) for auto-responses

   Applicable protocol: Mail [18]

   Status: standards-track

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 3282 [21]

   Related information:
      Indicates a language that the message sender requests to be used
      for responses.  Accept-language was not designed for email but has
      been considered useful as input to the generation of automatic
      replies.  Some problems have been noted concerning its use with
      email, including but not limited to determination of the email
      address to which it refers; cost and lack of effective
      internationalization of email responses; interpretation of
      language subtags; and determining what character set encoding
      should be used.

Top      ToC       Page 20 
2.1.28.  Header Field: Original-Message-ID

   Description:
      Original message identifier

   Applicable protocol: Mail [18]

   Status: standards-track

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 3297 [22]

   Related information:
      Original message identifier used with resend of message with
      alternative content format; identifies the original message data
      to which it corresponds.

2.1.29.  Header Field: PICS-Label

   Description:
      PICS rating label

   Applicable protocol: Mail [18]

   Status: standard

   Author/change controller:
      W3C  (mailto:web-human@w3.org)
      World Wide Web Consortium

   Specification document(s):
      PICS-labels [24]

   Related information:
      Ratings label to control selection (filtering) of messages
      according to the PICS protocol.  Specified for general use with
      RFC 822 message format, with HTTP-specific extensions.

Top      ToC       Page 21 
2.1.30.  Header Field: Encoding

   Description:
      Message encoding and other information

   Applicable protocol: Mail [18]

   Status: experimental

   Author/change controller:
      Albert K. Costanzo  (mailto:AL@AKC.COM)
      AKC Consulting Inc.

   Specification document(s):
      RFC 1505 [4]

   Related information:
      Used in several different ways by different mail systems.  Some
      use it for a kind of content-type information, some for encoding
      and length information, some for a kind of boundary information,
      and some in other ways.

2.1.31.  Header Field: List-Archive

   Description:
      URL of mailing list archive

   Applicable protocol: Mail [18]

   Status: standards-track

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2369 [13]

   Related information:
      Contains the URL to use to browse the archives of the mailing list
      from which this message was relayed.

Top      ToC       Page 22 
2.1.32.  Header Field: List-Help

   Description:
      URL for mailing list information

   Applicable protocol: Mail [18]

   Status: standards-track

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2369 [13]

   Related information:
      Contains the URL to use to get information about the mailing list
      from which this message was relayed.

2.1.33.  Header Field: List-ID

   Description:
      Mailing list identifier

   Applicable protocol: Mail [18]

   Status: standards-track

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2919 [20]

   Related information:
      Stores an identification of the mailing list through which this
      message was distributed.

Top      ToC       Page 23 
2.1.34.  Header Field: List-Owner

   Description:
      URL for mailing list owner's mailbox

   Applicable protocol: Mail [18]

   Status: standards-track

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2369 [13]

   Related information:
      Contains the URL to send e-mail to the owner of the mailing list
      from which this message was relayed.

2.1.35.  Header Field: List-Post

   Description:
      URL for mailing list posting

   Applicable protocol: Mail [18]

   Status: standards-track

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2369 [13]

   Related information:
      Contains the URL to use to send contributions to the mailing list
      from which this message was relayed.

Top      ToC       Page 24 
2.1.36.  Header Field: List-Subscribe

   Description:
      URL for mailing list subscription

   Applicable protocol: Mail [18]

   Status: standards-track

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2369 [13]

   Related information:
      Contains the URL to use to get a subscription to the mailing list
      from which this message was relayed.

2.1.37.  Header Field: List-Unsubscribe

   Description:
      URL for mailing list unsubscription

   Applicable protocol: Mail [18]

   Status: standards-track

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2369 [13]

   Related information:
      Contains the URL to use to unsubscribe the mailing list from which
      this message was relayed.

Top      ToC       Page 25 
2.1.38.  Header Field: Message-Context

   Description:
      Type or context of message

   Applicable protocol: Mail [18]

   Status: standards-track

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 3458 [23]

   Related information:
      Provides information about the context and presentation
      characteristics of a message.  Can have the values 'voice-
      message', 'fax-message', 'pager-message', 'multimedia-message',
      'text-message', or 'none'.

2.1.39.  Header Field: DL-Expansion-History

   Description:
      Trace of distribution lists passed

   Applicable protocol: Mail [18]

   Status: standards-track

   Author/change controller:
      IETF  (mailto:iesg@ietf.org)
      Internet Engineering Task Force

   Specification document(s):
      RFC 2156 [10]

   Related information:
      Trace of distribution lists passed. (MIXER X.400 mapping; not for
      general use.)


Next RFC Part