Network Working Group G. Klyne Internet-Draft Nine by Nine Expires: August 19, 2004 J. Palme Stockholm University/KTH February 19, 2004 Registration of mail and MIME header fields draft-klyne-hdrreg-mail-02 Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on August 19, 2004. Copyright Notice Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract This document defines the initial IANA registration for permanent mail and MIME message header fields, per [[[RFC XXXX]]] [1]. Discussion of this document Please send comments to . To subscribe to this list, send a message with the body 'subscribe' to . Klyne & Palme Expires August 19, 2004 [Page 1] Internet-Draft Mail/MIME header registration February 2004 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 4 1.1 Structure of this document . . . . . . . . . . . . . . . . 4 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 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-Message-ID . . . . . . . . . . . . . 16 2.1.21 Header field: Return-Path . . . . . . . . . . . . . . . . 16 2.1.22 Header field: Received . . . . . . . . . . . . . . . . . . 16 2.1.23 Header field: Disposition-Notification-To . . . . . . . . 17 2.1.24 Header field: Disposition-Notification-Options . . . . . . 17 2.1.25 Header field: Original-Recipient . . . . . . . . . . . . . 18 2.1.26 Header field: Originator . . . . . . . . . . . . . . . . . 18 2.1.27 Header field: PICS-Label . . . . . . . . . . . . . . . . . 19 2.1.28 Header field: Encoding . . . . . . . . . . . . . . . . . . 19 2.1.29 Header field: List-Archive . . . . . . . . . . . . . . . . 20 2.1.30 Header field: List-Help . . . . . . . . . . . . . . . . . 20 2.1.31 Header field: List-ID . . . . . . . . . . . . . . . . . . 21 2.1.32 Header field: List-Owner . . . . . . . . . . . . . . . . . 21 2.1.33 Header field: List-Post . . . . . . . . . . . . . . . . . 22 2.1.34 Header field: List-Subscribe . . . . . . . . . . . . . . . 22 2.1.35 Header field: List-Unsubscribe . . . . . . . . . . . . . . 23 2.1.36 Header field: Message-Context . . . . . . . . . . . . . . 23 2.1.37 Header field: DL-Expansion-History . . . . . . . . . . . . 24 2.1.38 Header field: Alternate-Recipient . . . . . . . . . . . . 24 2.1.39 Header field: Original-Encoded-Information-Types . . . . . 25 2.1.40 Header field: Content-Return . . . . . . . . . . . . . . . 25 2.1.41 Header field: Generate-Delivery-Report . . . . . . . . . . 26 Klyne & Palme Expires August 19, 2004 [Page 2] Internet-Draft Mail/MIME header registration February 2004 2.1.42 Header field: Prevent-NonDelivery-Report . . . . . . . . . 26 2.1.43 Header field: Obsoletes . . . . . . . . . . . . . . . . . 27 2.1.44 Header field: Content-Identifier . . . . . . . . . . . . . 27 2.1.45 Header field: Delivery-Date . . . . . . . . . . . . . . . 28 2.1.46 Header field: Expiry-Date . . . . . . . . . . . . . . . . 28 2.1.47 Header field: Reply-By . . . . . . . . . . . . . . . . . . 29 2.1.48 Header field: Importance . . . . . . . . . . . . . . . . . 29 2.1.49 Header field: Incomplete-Copy . . . . . . . . . . . . . . 30 2.1.50 Header field: Priority . . . . . . . . . . . . . . . . . . 30 2.1.51 Header field: Sensitivity . . . . . . . . . . . . . . . . 31 2.1.52 Header field: Language . . . . . . . . . . . . . . . . . . 32 2.1.53 Header field: Conversion . . . . . . . . . . . . . . . . . 32 2.1.54 Header field: Conversion-With-Loss . . . . . . . . . . . . 33 2.1.55 Header field: Message-Type . . . . . . . . . . . . . . . . 33 2.1.56 Header field: Autoforwarded . . . . . . . . . . . . . . . 34 2.1.57 Header field: Discarded-X400-IPMS-Extensions . . . . . . . 34 2.1.58 Header field: Discarded-X400-MTS-Extensions . . . . . . . 35 2.1.59 Header field: Disclose-Recipients . . . . . . . . . . . . 35 2.2 Permanent MIME header field registrations . . . . . . . . 36 2.2.1 Header field: MIME-Version . . . . . . . . . . . . . . . . 36 2.2.2 Header field: Content-ID . . . . . . . . . . . . . . . . . 37 2.2.3 Header field: Content-Description . . . . . . . . . . . . 37 2.2.4 Header field: Content-Transfer-Encoding . . . . . . . . . 38 2.2.5 Header field: Content-Type . . . . . . . . . . . . . . . . 38 2.2.6 Header field: Content-Base . . . . . . . . . . . . . . . . 39 2.2.7 Header field: Content-Location . . . . . . . . . . . . . . 39 2.2.8 Header field: Content-features . . . . . . . . . . . . . . 40 2.2.9 Header field: Content-Disposition . . . . . . . . . . . . 40 2.2.10 Header field: Content-Language . . . . . . . . . . . . . . 41 2.2.11 Header field: Content-Alternative . . . . . . . . . . . . 41 2.2.12 Header field: Content-MD5 . . . . . . . . . . . . . . . . 42 3. IANA considerations . . . . . . . . . . . . . . . . . . . 42 4. Security considerations . . . . . . . . . . . . . . . . . 42 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . 42 References . . . . . . . . . . . . . . . . . . . . . . . . 43 Authors' Addresses . . . . . . . . . . . . . . . . . . . . 44 A. Revision history . . . . . . . . . . . . . . . . . . . . . 45 A.1 draft-klyne-hdrreg-mail-02 . . . . . . . . . . . . . . . . 45 A.2 draft-klyne-hdrreg-mail-01 . . . . . . . . . . . . . . . . 45 A.3 draft-klyne-hdrreg-mail-00 . . . . . . . . . . . . . . . . 46 B. TODO: . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Intellectual Property and Copyright Statements . . . . . . 47 Klyne & Palme Expires August 19, 2004 [Page 3] Internet-Draft Mail/MIME header registration February 2004 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. Some sample HTML registry pages have been prepared from the same data, and can be found at [21].]]] 1.1 Structure of this document Section Section 2 contains the submission for initial registration of mail related message headers 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 RFC 2119 [10]. NOTE: indented comments like this provide additional nonessential information about the rationale behind this document. [[[Editorial comments and questions about outstanding issues are provided in triple brackets like this. These working comments should be resolved and removed prior to final publication.]]] 2. Registration templates Header 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 Klyne & Palme Expires August 19, 2004 [Page 4] Internet-Draft Mail/MIME header registration February 2004 In-Reply-To Mail Original message identifier(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-Message-ID Mail Message identifier for resent message Return-Path Mail Message return path Received Mail Mail transfer trace information Disposition-Notification-To Mail Mailbox for sending disposition notification Disposition-Notification-Options Mail Disposition notification options Original-Recipient Mail MDN original recipient information Originator Mail Similar to 'Sender:' 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 Klyne & Palme Expires August 19, 2004 [Page 5] Internet-Draft Mail/MIME header registration February 2004 Mail Request delivery report generation Prevent-NonDelivery-Report Mail Non-delivery report required? Obsoletes Mail Reference message to be replaced Content-Identifier Mail Message content identifier Delivery-Date Mail Message delivery time Expiry-Date 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 lenguage Conversion Mail Conversion allowed? Conversion-With-Loss Mail Lossy conversion allowed? Message-Type Mail Message type: delivery report? 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? Figure 1 2.1.1 Header field: Date Description: Message date and time Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.1) Klyne & Palme Expires August 19, 2004 [Page 6] Internet-Draft Mail/MIME header registration February 2004 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. 2.1.2 Header field: From Description: Mailbox of message author Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (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. 2.1.3 Header field: Sender Description: Mailbox of message sender Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.2) Klyne & Palme Expires August 19, 2004 [Page 7] Internet-Draft Mail/MIME header registration February 2004 Related information: Specifies the mailbox of the agent responsible for the actual transmission of the message. 2.1.4 Header field: Reply-To Description: Mailbox for replies to message Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (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. 2.1.5 Header field: To Description: Primary recipient mailbox Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.3) Klyne & Palme Expires August 19, 2004 [Page 8] Internet-Draft Mail/MIME header registration February 2004 Related information: Contains the address(es) of the primary recipient(s) of the message. 2.1.6 Header field: Cc Description: Carbon-copy recipient mailbox Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (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. 2.1.7 Header field: Bcc Description: Blind-carbon-copy recipient mailbox Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.3) Klyne & Palme Expires August 19, 2004 [Page 9] Internet-Draft Mail/MIME header registration February 2004 Related information: Contains addresses of recipients of the message whose addresses are not to be revealed to other recipients of the message. 2.1.8 Header field: Message-ID Description: Message identifier Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (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. 2.1.9 Header field: In-Reply-To Description: Original message identifier(s) Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.4) Klyne & Palme Expires August 19, 2004 [Page 10] Internet-Draft Mail/MIME header registration February 2004 Related information: The message identifier(s) of the original message(s) to which the current message is a reply. 2.1.10 Header field: References Description: Related message identifier(s) Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.4) Related information: The message identifier(s) of other message(s) to which the current message may be related. In RFC2822, the definition was changed to say that this header field contains a list of all Message-IDs of messages in the preceding reply chain. 2.1.11 Header field: Subject Description: Topic of message Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.5) Klyne & Palme Expires August 19, 2004 [Page 11] Internet-Draft Mail/MIME header registration February 2004 Related information: Contains a short string identifying the topic of the message. 2.1.12 Header field: Comments Description: Additional comments about the message Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (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. 2.1.13 Header field: Keywords Description: Message key words and/or phrases Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.5) Klyne & Palme Expires August 19, 2004 [Page 12] Internet-Draft Mail/MIME header registration February 2004 Related information: Contains a comma-separated list of important words and phrases that might be useful for the recipient. 2.1.14 Header field: Resent-Date Description: Date and time message is resent Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.6) Related information: Contains the date and time that a message is reintroduced into the message transfer system. 2.1.15 Header field: Resent-From Description: Mailbox of person for whom message is resent Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.6) Klyne & Palme Expires August 19, 2004 [Page 13] Internet-Draft Mail/MIME header registration February 2004 Related information: Contains the mailbox of the agent who has reintroduced the message into the message transfer system, or on whose behanlf the message has been resent. 2.1.16 Header field: Resent-Sender Description: Mailbox of person who actually resends the message Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (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. 2.1.17 Header field: Resent-To Description: Mailbox to which message is resent Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.6) Klyne & Palme Expires August 19, 2004 [Page 14] Internet-Draft Mail/MIME header registration February 2004 Related information: Contains the mailbox(es) to which the message has been resent. 2.1.18 Header field: Resent-Cc Description: Mailbox(es) to which message is cc'ed on resend Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.6) Related information: Containes the mailbox(es) to which message is cc'ed on resend 2.1.19 Header field: Resent-Bcc Description: Mailbox(es) to which message is bcc'ed on resend Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.6) Related information: Containes the mailbox(es) to which message is bcc'ed on resend Klyne & Palme Expires August 19, 2004 [Page 15] Internet-Draft Mail/MIME header registration February 2004 2.1.20 Header field: Resent-Message-ID Description: Message identifier for resent message Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.6) Related information: Contains a message identifier for a resent message 2.1.21 Header field: Return-Path Description: Message return path Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.7) Related information: Return path for message response diagnostics. See also, RFC 2821. 2.1.22 Header field: Received Klyne & Palme Expires August 19, 2004 [Page 16] Internet-Draft Mail/MIME header registration February 2004 Description: Mail transfer trace information Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2822.txt (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. 2.1.23 Header field: Disposition-Notification-To Description: Mailbox for sending disposition notification Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2298.txt Related information: Indicates that the sender wants a disposition notification when this message is received (read, processed, etc.) by its recipients. 2.1.24 Header field: Disposition-Notification-Options Klyne & Palme Expires August 19, 2004 [Page 17] Internet-Draft Mail/MIME header registration February 2004 Description: Disposition notification options Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2298.txt Related information: For optional modifiers on disposition notification requests. 2.1.25 Header field: Original-Recipient Description: MDN original recipient information Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2298.txt Related information: Original Recipient information for inclusion in disposition notifications. 2.1.26 Header field: Originator Description: Similar to 'Sender:' Klyne & Palme Expires August 19, 2004 [Page 18] Internet-Draft Mail/MIME header registration February 2004 Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: experimental Author/change controller: Carl Malamud (mailto:carl@malamud.com) Internet Multicasting Service. Specification document(s): http://www.rfc-editor.org/rfc/rfc1528.txt Related information: Sometimes used in Usenet News in similar ways to 'Sender:' Also used in printing protocols. Non-standard in Usenet News, Experimental in RFC 1528 (tcp.int). 2.1.27 Header field: PICS-Label Description: PICS rating label Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standard Author/change controller: W3C (mailto:web-human@w3.org) World Wide Web Consortium. Specification document(s): http://www.w3.org/TR/REC-PICS-labels Related information: Ratings label to control selection (filtering) of messages according to the PICS protocol. Specified for general use with RFC822 message format, with HTTP-specific extensions 2.1.28 Header field: Encoding Description: Message encoding and other information Klyne & Palme Expires August 19, 2004 [Page 19] Internet-Draft Mail/MIME header registration February 2004 Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: experimental Author/change controller: Albert K. Costanzo (mailto:AL@AKC.COM) AKC Consulting Inc.. Specification document(s): http://www.rfc-editor.org/rfc/rfc1505.txt 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, some in other ways. 2.1.29 Header field: List-Archive Description: URL of mailing list archive Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2369.txt Related information: Contains URL to use to browse the archives of the mailing list from which this message was relayed. 2.1.30 Header field: List-Help Description: URL for mailing list information Klyne & Palme Expires August 19, 2004 [Page 20] Internet-Draft Mail/MIME header registration February 2004 Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2369.txt Related information: Contains URL to use to get a information about the mailing list from which this message was relayed. 2.1.31 Header field: List-ID Description: Mailing list identifier Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc1919.txt Related information: Stores an identification of the mailing list, through which this message was distributed. 2.1.32 Header field: List-Owner Description: URL for mailing list owner's mailbox Klyne & Palme Expires August 19, 2004 [Page 21] Internet-Draft Mail/MIME header registration February 2004 Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2369.txt Related information: Contains URL to send e-mail to the owner of the mailing list from which this message was relayed. 2.1.33 Header field: List-Post Description: URL for mailing list posting Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2369.txt Related information: Contains URL to use to send contributions to the mailing list from which this message was relayed. 2.1.34 Header field: List-Subscribe Description: URL for mailing list subscription Klyne & Palme Expires August 19, 2004 [Page 22] Internet-Draft Mail/MIME header registration February 2004 Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2369.txt Related information: Contains URL to use to get a subscription to the mailing list from which this message was relayed. 2.1.35 Header field: List-Unsubscribe Description: URL for mailing list unsubscription Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2369.txt Related information: Contains URL to use to unsubscribe the mailing list from which this message was relayed. 2.1.36 Header field: Message-Context Description: Type or context of message Klyne & Palme Expires August 19, 2004 [Page 23] Internet-Draft Mail/MIME header registration February 2004 Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: Standards track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc3458.txt 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', 'none'. 2.1.37 Header field: DL-Expansion-History Description: Trace of distribution lists passed Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: Trace of distribution lists passed. (MIXER X.400 mapping, not for general use.) 2.1.38 Header field: Alternate-Recipient Description: Controls forwarding to alternate recipients Klyne & Palme Expires August 19, 2004 [Page 24] Internet-Draft Mail/MIME header registration February 2004 Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: Controls whether this message may be forwarded to alternate recipients such as a postmaster if delivery is not possible to the intended recipient. Default: Allowed. RFC 2156 (MIXER), not for general usage. 2.1.39 Header field: Original-Encoded-Information-Types Description: Body part types in message Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: Which body part types occur in this message. RFC 2156 (MIXER), not for general use. 2.1.40 Header field: Content-Return Description: Return content on non-delivery? Klyne & Palme Expires August 19, 2004 [Page 25] Internet-Draft Mail/MIME header registration February 2004 Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: Indicates whether the content of a message is to be returned with non-delivery notifications. RFC 2156 (MIXER), not for general use. 2.1.41 Header field: Generate-Delivery-Report Description: Request delivery report generation Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: Indicates whether a delivery report is wanted at successful delivery. Default is not to generate such a report. RFC 2156 (MIXER), not for general usage. 2.1.42 Header field: Prevent-NonDelivery-Report Description: Non-delivery report required? Klyne & Palme Expires August 19, 2004 [Page 26] Internet-Draft Mail/MIME header registration February 2004 Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: Indicates whether non-delivery report is wanted on delivery error. Default is to generate such a report. RFC 2156 (MIXER), not for general usage. 2.1.43 Header field: Obsoletes Description: Reference message to be replaced Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: Reference to a previous message being corrected and replaced. Compare to 'Supersedes:' used in Usenet News. This field may in the future be replaced with a different name. RFC 2156 (MIXER), not for general usage. 2.1.44 Header field: Content-Identifier Klyne & Palme Expires August 19, 2004 [Page 27] Internet-Draft Mail/MIME header registration February 2004 Description: Message content identifier Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: A text string which identifies the content of a message. RFC 2156 (MIXER), not for general usage. 2.1.45 Header field: Delivery-Date Description: Message delivery time Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: The time when a message was delivered to its recipient. RFC 2156 (MIXER), not for general use. 2.1.46 Header field: Expiry-Date Klyne & Palme Expires August 19, 2004 [Page 28] Internet-Draft Mail/MIME header registration February 2004 Description: Message expiry time Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: Time at which a message loses its validity. This field may in the future be replaced by 'Expires:'. RFC 2156 (MIXER), not for general use. 2.1.47 Header field: Reply-By Description: Time by which a reply is requested Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: Latest time at which a reply is requested (not demanded). RFC 2156 (MIXER), not for general usage. 2.1.48 Header field: Importance Klyne & Palme Expires August 19, 2004 [Page 29] Internet-Draft Mail/MIME header registration February 2004 Description: Message importance Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: A hint from the originator to the recipients about how important a message is. Values: High, normal or low. Not used to control transmission speed. Proposed for use with RFC 2156 (MIXER) and RFC 2421 (VPIM). 2.1.49 Header field: Incomplete-Copy Description: Body parts are missing. Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: Body parts are missing. RFC 2156 (MIXER), not for general usage. 2.1.50 Header field: Priority Klyne & Palme Expires August 19, 2004 [Page 30] Internet-Draft Mail/MIME header registration February 2004 Description: Message priority Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: Can be 'normal', 'urgent' or 'non-urgent' and can influence transmission speed and delivery. RFC 2156 (MIXER), not for general use. 2.1.51 Header field: Sensitivity Description: Message content sensitivity Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: How sensitive it is to disclose this message to other people than the specified recipients. Values: Personal, private, company confidential. The absence of this header field in messages gatewayed from X.400 indicates that the message is not sensitive. Proposed for use with RFC 2156 (MIXER) and RFC 2421 (VPIM). Klyne & Palme Expires August 19, 2004 [Page 31] Internet-Draft Mail/MIME header registration February 2004 2.1.52 Header field: Language Description: X.400 message content lenguage Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: Can include a code for the natural language used in a message, e.g. 'en' for English. See also 'Content-Language'. RFC 2156 (MIXER), not for general usage. 2.1.53 Header field: Conversion Description: Conversion allowed? Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: The body of this message may not be converted from one character set to another. Values: Prohibited and allowed. RFC 2156 (MIXER), not for general use. Klyne & Palme Expires August 19, 2004 [Page 32] Internet-Draft Mail/MIME header registration February 2004 2.1.54 Header field: Conversion-With-Loss Description: Lossy conversion allowed? Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: The body of this message may not be converted from one character set to another if information will be lost. Values: Prohibited and allowed. RFC 2156 (MIXER), not for general use. 2.1.55 Header field: Message-Type Description: Message type: delivery report? Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: Only used with the value 'Delivery Report' to indicates that this is a delivery report gatewayed from X.400. RFC 2156 (MIXER), not for general use. Klyne & Palme Expires August 19, 2004 [Page 33] Internet-Draft Mail/MIME header registration February 2004 2.1.56 Header field: Autoforwarded Description: Automatically forwarded indicator Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: Has been automatically forwarded. RFC 2156 (MIXER), not for general usage. 2.1.57 Header field: Discarded-X400-IPMS-Extensions Description: X.400 IPM extensions discarded Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: Can be used in Internet mail to indicate X.400 IPM extensions which could not be mapped to Internet mail format. RFC 2156 (MIXER), not for general usage. Klyne & Palme Expires August 19, 2004 [Page 34] Internet-Draft Mail/MIME header registration February 2004 2.1.58 Header field: Discarded-X400-MTS-Extensions Description: X.400 MTS extensions discarded Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: Can be used in Internet mail to indicate X.400 MTS extensions which could not be mapped to Internet mail format. RFC 2156 (MIXER), not for general usage. 2.1.59 Header field: Disclose-Recipients Description: Disclose names of other recipients? Applicable protocol: Mail (http://www.rfc-editor.org/rfc/rfc2822.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2156.txt Related information: Tells whether recipients are to be told the names of other recipients of the same message. This is primarily an X.400 facility. In X.400, this is an envelope attribute and refers to disclosure of the envelope recipient list. Disclosure of other recipients is in Internet mail done via the To:, cc: and bcc: Klyne & Palme Expires August 19, 2004 [Page 35] Internet-Draft Mail/MIME header registration February 2004 header fields. Not for general use. 2.2 Permanent MIME header field registrations Header name Protocol ----------- -------- MIME-Version MIME MIME version number Content-ID MIME Identify content body part Content-Description MIME Description of message body part Content-Transfer-Encoding MIME Content transfer encoding applied Content-Type MIME MIME content type Content-Base MIME Base to be used for resolving relative URIs within this content part. Content-Location MIME URI for retrieving a body part Content-features MIME Indicates content features of a MIME body part Content-Disposition MIME Intended content disposition and file name Content-Language MIME Language of message content Content-Alternative MIME Alternative content available Content-MD5 MIME MD5 checksum of content Figure 2 2.2.1 Header field: MIME-Version Description: MIME version number Applicable protocol: MIME (http://www.rfc-editor.org/rfc/rfc2045.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2045.txt (section 4) Klyne & Palme Expires August 19, 2004 [Page 36] Internet-Draft Mail/MIME header registration February 2004 Related information: An indicator that this message is formatted according to the MIME standard, and an indication of which version of MIME is utilized. 2.2.2 Header field: Content-ID Description: Identify content body part Applicable protocol: MIME (http://www.rfc-editor.org/rfc/rfc2045.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2045.txt (section 7) Related information: Specifies a Unique ID for one MIME body part of the content of a message. 2.2.3 Header field: Content-Description Description: Description of message body part Applicable protocol: MIME (http://www.rfc-editor.org/rfc/rfc2045.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2045.txt (section 8) Klyne & Palme Expires August 19, 2004 [Page 37] Internet-Draft Mail/MIME header registration February 2004 Related information: Description of a particular body part of a message, for example a caption for an image body part. 2.2.4 Header field: Content-Transfer-Encoding Description: Content transfer encoding applied Applicable protocol: MIME (http://www.rfc-editor.org/rfc/rfc2045.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2045.txt (section 6) Related information: Coding method used in a MIME message body part. 2.2.5 Header field: Content-Type Description: MIME content type Applicable protocol: MIME (http://www.rfc-editor.org/rfc/rfc2045.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2045.txt (section 5) Related information: Format of content (character set etc.) Note that the values for this header field are defined in different ways in RFC 1049 and in Klyne & Palme Expires August 19, 2004 [Page 38] Internet-Draft Mail/MIME header registration February 2004 MIME (RFC 2045), look for the 'MIME-version' header field to understand if Content-Type is to be interpreted according to RFC 1049 or according to MIME. The MIME definition should be used in generating mail. RFC 1049 has 'historic' status. RFC 1766 defines a parameter 'difference' to this header field. Various other Content-Type define various additional parameters. For example, the parameter 'charset' is mandatory for all textual Content-Types. See also: RFC 1049, RFC 1123: 5.2.13, RFC 1766: 4.1. 2.2.6 Header field: Content-Base Description: Base to be used for resolving relative URIs within this content part. Applicable protocol: MIME (http://www.rfc-editor.org/rfc/rfc2045.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2110.txt Related information: Base to be used for resolving relative URIs within this content part. 2.2.7 Header field: Content-Location Description: URI for retrieving a body part Applicable protocol: MIME (http://www.rfc-editor.org/rfc/rfc2045.txt) Status: standards-track Klyne & Palme Expires August 19, 2004 [Page 39] Internet-Draft Mail/MIME header registration February 2004 Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2110.txt Related information: URI using which the content of this body-part part was retrieved, might be retrievable, or which otherwise gives a globally unique identification of the content. 2.2.8 Header field: Content-features Description: Indicates content features of a MIME body part Applicable protocol: MIME (http://www.rfc-editor.org/rfc/rfc2045.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2912.txt (section 3) Related information: The 'Content-features:' header can be used to annotate a MIME body part with a media feature expression, to indicate features of the body part content. See also: RFC 2533, RFC 2506, RFC 2045. 2.2.9 Header field: Content-Disposition Description: Intended content disposition and file name Applicable protocol: MIME (http://www.rfc-editor.org/rfc/rfc2045.txt) Status: experimental Klyne & Palme Expires August 19, 2004 [Page 40] Internet-Draft Mail/MIME header registration February 2004 Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc2183.txt Related information: Whether a MIME body part is to be shown inline or is an attachment; can also indicate a suggested filename for use when saving an attachment to a file. 2.2.10 Header field: Content-Language Description: Language of message content Applicable protocol: MIME (http://www.rfc-editor.org/rfc/rfc2045.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc3282.txt Related information: Can include a code for the natural language used in a message, e.g. 'en' for English. Can also contain a list of languages for a message containing more than one language. 2.2.11 Header field: Content-Alternative Description: Alternative content available Applicable protocol: MIME (http://www.rfc-editor.org/rfc/rfc2045.txt) Status: work-in-progress Klyne & Palme Expires August 19, 2004 [Page 41] Internet-Draft Mail/MIME header registration February 2004 Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc3297.txt Related information: Information about the media features of alternative content formats available for the current message. 2.2.12 Header field: Content-MD5 Description: MD5 checksum of content Applicable protocol: MIME (http://www.rfc-editor.org/rfc/rfc2045.txt) Status: standards-track Author/change controller: IETF (mailto:iesg@ietf.org) Internet Engineering Task Force. Specification document(s): http://www.rfc-editor.org/rfc/rfc1864.txt Related information: Checksum of content to ensure that it has not been modified. 3. IANA considerations This specification provides initial registrations of mail and MIME headers in the "Permanent Message Header Field Registry", defined by Registration procedures for message header fields [1]. 4. Security considerations No security considerations are introduced by this specification beyond those already inherent in the use of message headers. 5. Acknowledgements Most of the information in this document has been derived from Jacob Klyne & Palme Expires August 19, 2004 [Page 42] Internet-Draft Mail/MIME header registration February 2004 Palme's work in RFC 2076 [8] and subsequent updates [20]. The authors also gratefully acknowledge the contributions of: Mark Nottingham, [[[...]]] References [1] Klyne, G., Nottingham, M. and J. Mogul, "Registration procedures for message headers", Oct 2003, . [2] Alvestrand, H., Jordan, K. and J. Romaguera, "Rules for downgrading messages from X.400/88 to X.400/84 when MIME content-types are present in the messages", RFC 1496, August 1993. [3] Costanzo, A., Robinson, D. and R. Ullmann, "Encoding Header Field for Internet Messages", RFC 1505, August 1993. [4] Alvestrand, H., "Tags for the Identification of Languages", RFC 1766, March 1995. [5] Myers, J. and M. Rose, "The Content-MD5 Header Field", RFC 1864, October 1995. [6] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, November 1996. [7] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types", RFC 2046, November 1996. [8] Palme, J., "Common Internet Message Headers", RFC 2076, February 1997. [9] Palme, J. and A. Hopmann, "MIME E-mail Encapsulation of Aggregate Documents, such as HTML (MHTML)", RFC 2110, March 1997. [10] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [11] Kille, S., "MIXER (Mime Internet X.400 Enhanced Relay): Mapping between X.400 and RFC 822/MIME", RFC 2156, January 1998. [12] Troost, R., Dorner, S. and K. Moore, "Communicating Klyne & Palme Expires August 19, 2004 [Page 43] Internet-Draft Mail/MIME header registration February 2004 Presentation Information in Internet Messages: The Content-Disposition Header Field", RFC 2183, August 1997. [13] Fajman, R., "An Extensible Message Format for Message Disposition Notifications", RFC 2298, March 1998. [14] Neufeld, G. and J. Baer, "The Use of URLs as Meta-Syntax for Core Mail List Commands and their Transport through Message Header Fields", RFC 2369, July 1998. [15] Vaudreuil, G. and G. Parsons, "Voice Profile for Internet Mail - version 2", RFC 2421, September 1998. [16] Klensin, J., "Simple Mail Transfer Protocol", RFC 2821, April 2001. [17] Resnick, P., "Internet Message Format", RFC 2822, April 2001. [18] Klyne, G., "Indicating Media Features for MIME Content", RFC 2912, September 2000. [19] Chandhok, R. and G. Wenger, "List-Id: A Structured Field and Namespace for the Identification of Mailing Lists", RFC 2919, March 2001. [20] Palme, J., "Common Internet Message Header Fields", Internet draft draft-palme-mailext-headers-06, November 2001, . [21] Authors' Addresses Graham Klyne Nine by Nine UK EMail: GK-IETF@ninebynine.org URI: http://www.ninebynine.net/ Klyne & Palme Expires August 19, 2004 [Page 44] Internet-Draft Mail/MIME header registration February 2004 Jacob Palme Stockholm University/KTH Forum 100 Kista S-164 40 Sweden Phone: +46-8-16 16 67 EMail: jpalme@dsv.su.se Appendix A. Revision history [[[Please remove this section on final publication]]] A.1 draft-klyne-hdrreg-mail-02 02d 19-Feb-2004: * Incorporated small changes to specific header field descriptions, suggested by Jacob. 02c 18-Feb-2004: * Separated Mail and MIME header fields. * Corrected specification reference for MIXER headers (RFC 2156). * Changed applicable protocol for MIME header fields. * Other smaller corrections. 02b 17-Feb-2004: * Removed provisional mail header registrations from this document. 02a 05-Aug-2002: * Added Jacob Palme as co-editor. A.2 draft-klyne-hdrreg-mail-01 01c 05-Jun-2002: * Minor editorial. Klyne & Palme Expires August 19, 2004 [Page 45] Internet-Draft Mail/MIME header registration February 2004 01b 10-May-2002: * Updated some contact information. * Regenerated registry tables with revised software. 01a 08-May-2002: * Revised change controller information in line with registry specification. * Cleaned up some table layout. A.3 draft-klyne-hdrreg-mail-00 00c 05-May-2002: * Added data for permanent and provisional registries. 00b 01-May-2002: * Revised form of registry entry content. (Auto-generated from RDF data.) 00a 22-Jan-2002: * Document initially created. Appendix B. TODO: [[[Please remove this section on final publication]]] o Review format of header descriptions: may want to make this more compact. 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