TOC 
Network Working GroupG. Klyne
Internet-DraftClearswift
Expires: November 3, 2002May 05, 2002

Registration of mail header fields
draft-klyne-hdrreg-mail-00

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.

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This Internet-Draft will expire on November 3, 2002.

Copyright Notice

Copyright (C) The Internet Society (2002). All Rights Reserved.

Abstract

This document defines the initial IANA registration for some mail message header fields.

Discussion of this document

Please send comments to <ietf-822@imc.org>. To subscribe to this list, send a message with the body 'subscribe' to <ietf-822-request@imc.org>.


 TOC 

Table of Contents
 TOC 

1. Introduction

This document defines IANA registration for a number of mail message 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 http://www.ninebynine.org/IETF/Messaging/HdrRegistry/Intro.html.

1.1 Structure of this document

Section Registration templates 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.]]]


 TOC 

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 header registrations

Header name         Protocol  Description
-----------         --------  -----------
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      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
Content-features    mail      Indicates content features of a
                              MIME body part
Content-Disposition mail      Intended content disposition and
                              file name
Disclose-Recipients mail      Disclose names of other
                              recipients?
Originator          mail      Similar to 'Sender:'
PICS-Label          mail      PICS rating label
Content-Language    mail      Language of message content
Content-Alternative mail      Alternative content available
Encoding            mail      Message encoding and other
                              information
Content-MD5         mail      MD5 checksum of content
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
MIME-Version        mail      MIME version number
Content-ID          mail      Identify content body part
Content-Description mail      Description of message body part
Content-Transfer-Encodingmail Content transfer encoding applied
Content-Type        mail      MIME content type
Disposition-Notification-Tomail Mailbox for sending disposition
                              notification
Disposition-Notification-Optionsmail Disposition notification
                              options
Original-Recipient  mail      MDN original recipient information
Content-Base        mail      Base to be used for resolving
                              relative URIs within this content
                              part.
Content-Location    mail      URI for retrieving a body part
DL-Expansion-Historymail      Trace of distribution lists passed
Alternate-Recipient mail      Controls forwarding to alternate
                              recipients
Original-Encoded-Information-Typesmail Body part types in
                              message
Content-Return      mail      Return content on non-delivery?
X400-Content-Return mail      Possible future name for
                              'Content-Return:'
Generate-Delivery-Reportmail  Request delivery report generation
Prevent-NonDelivery-Reportmail 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-Lossmail      Lossy conversion allowed?
Message-Type        mail      Message type: delivery report?
Autoforwarded       mail      Automatically forwarded indicator
Discarded-X400-IPMS-Extensionsmail X.400 IPM extensions
                              discarded
Discarded-X400-MTS-Extensionsmail X.400 MTS extensions discarded

2.1.1 Date: header

Header name:
Date
Description:
Message date and time
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
standards-track
Author/change controller:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
Specification document(s):
http://www.rfc-editor.org/rfc/rfc2822.txt (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.

2.1.2 From: header

Header name:
From
Description:
Mailbox of message author
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
standards-track
Author/change controller:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
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 Sender: header

Header name:
Sender
Description:
Mailbox of message sender
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
standards-track
Author/change controller:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
Specification document(s):
http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.2)
Related information:
Specifies the mailbox of the agent responsible for the actual transmission of the message.

2.1.4 Reply-To: header

Header name:
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:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
Specification document(s):
http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.2)
Related information:
When the R"eply-To: "field is present, it indicates the mailbox(es) to which the author of the message suggests that replies be sent.

2.1.5 To: header

Header name:
To
Description:
Primary recipient mailbox
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
standards-track
Author/change controller:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
Specification document(s):
http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.3)
Related information:
Contains the address(es) of the primary recipient(s) of the message.

2.1.6 Cc: header

Header name:
Cc
Description:
Carbon-copy recipient mailbox
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
standards-track
Author/change controller:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
Specification document(s):
http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.3)
Related information:
Bontains 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 Bcc: header

Header name:
Bcc
Description:
Blind-carbon-copy recipient mailbox
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
standards-track
Author/change controller:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
Specification document(s):
http://www.rfc-editor.org/rfc/rfc2822.txt (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.

2.1.8 Message-ID: header

Header name:
Message-ID
Description:
Message identifier
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
standards-track
Author/change controller:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
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.

2.1.9 In-Reply-To: header

Header name:
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:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
Specification document(s):
http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.4)
Related information:
The message identifier(s) of the original message(s) to which the current message is a reply.

2.1.10 References: header

Header name:
References
Description:
Related message identifier(s)
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
standards-track
Author/change controller:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
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.

2.1.11 Subject: header

Header name:
Subject
Description:
Topic of message
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
standards-track
Author/change controller:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
Specification document(s):
http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.5)
Related information:
Contains a short string identifying the topic of the message.

2.1.12 Comments: header

Header name:
Comments
Description:
Additional comments about the message
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
standards-track
Author/change controller:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
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.

2.1.13 Keywords: header

Header name:
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:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
Specification document(s):
http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.5)
Related information:
Contains a comma-separated list of important words and phrases that might be useful for the recipient.

2.1.14 Resent-Date: header

Header name:
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:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
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 Resent-From: header

Header name:
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:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
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, or on whose behanlf the message has been resent.

2.1.16 Resent-Sender: header

Header name:
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:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
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 Resent-To: header

Header name:
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:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
Specification document(s):
http://www.rfc-editor.org/rfc/rfc2822.txt (section 3.6.6)
Related information:
Contains the mailbox(es) to which the message has been resent.

2.1.18 Resent-Cc: header

Header name:
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:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
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 Resent-Bcc: header

Header name:
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:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
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

2.1.20 Resent-Message-ID: header

Header name:
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:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
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 Return-Path: header

Header name:
Return-Path
Description:
Message return path
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
standards-track
Author/change controller:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
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 Received: header

Header name:
Received
Description:
Mail transfer trace information
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
standards-track
Author/change controller:
Peter W. Resnick (mailto:presnick@qualcomm.com)
QUALCOMM Incorporated, 5775 Morehouse Drive,
San Diego, CA 92121-1714, USA.
Tel: +1 858 651 4478
Fax: +1 858 651 1102
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 Content-features: header

Header name:
Content-features
Description:
Indicates content features of a MIME body part
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
standards-track
Author/change controller:
Graham Klyne (mailto:GK-headers@ninebynine.org)
Clearswift Corporation,
1310 Waterside, Arlington Business Park, Theale,
Reading, RG7 4SA, UK.
Tel: 011 8903 8903
Fax: 011 8903 9000
URL: http://www.mimesweeper.com/
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.

2.1.24 Content-Disposition: header

Header name:
Content-Disposition
Description:
Intended content disposition and file name
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
experimental
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.

2.1.25 Disclose-Recipients: header

Header name:
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/rfc2822.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: header fields. Not for general use.

2.1.26 Originator: header

Header name:
Originator
Description:
Similar to 'Sender:'
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
experimental
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force, .
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 PICS-Label: header

Header name:
PICS-Label
Description:
PICS rating label
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
standards-track
Author/change controller:
W3C (mailto:xxxx@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 Content-Language: header

Header name:
Content-Language
Description:
Language of message content
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/rfc1766.txt
Related information:
Can include a code for the natural language used in a message, e.g. 'en' for English.

2.1.29 Content-Alternative: header

Header name:
Content-Alternative
Description:
Alternative content available
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
work-in-progress
Author/change controller:
Graham Klyne (mailto:GK-headers@ninebynine.org)
Clearswift Corporation,
1310 Waterside, Arlington Business Park, Theale,
Reading, RG7 4SA, UK.
Tel: 011 8903 8903
Fax: 011 8903 9000
URL: http://www.mimesweeper.com/
Specification document(s):
http://www.ietf.org/internet-drafts/draft-ietf-fax-content-negotiation-05.txt
Related information:
Information about the media features of alternative content formats available for the current message.

2.1.30 Encoding: header

Header name:
Encoding
Description:
Message encoding and other information
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
experimental
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force, .
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.

2.1.31 Content-MD5: header

Header name:
Content-MD5
Description:
MD5 checksum of content
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/rfc1864.txt
Related information:
Checksum of content to ensure that it has not been modified.

2.1.32 List-Archive: header

Header name:
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.

2.1.33 List-Help: header

Header name:
List-Help
Description:
URL for mailing list 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/rfc2369.txt
Related information:
Contains URL to use to get a information about the mailing list from which this message was relayed.

2.1.34 List-ID: header

Header name:
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.

2.1.35 List-Owner: header

Header name:
List-Owner
Description:
URL for mailing list owner's 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/rfc2369.txt
Related information:
Contains URL to send e-mail to the owner of the mailing list from which this message was relayed.

2.1.36 List-Post: header

Header name:
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.

2.1.37 List-Subscribe: header

Header name:
List-Subscribe
Description:
URL for mailing list subscription
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.

2.1.38 List-Unsubscribe: header

Header name:
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.

2.1.39 MIME-Version: header

Header name:
MIME-Version
Description:
MIME version number
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/rfc2045.txt (section 4)
Related information:
An indicator that this message is formatted according to the MIME standard, and an indication of which version of MIME is utilized.

2.1.40 Content-ID: header

Header name:
Content-ID
Description:
Identify content body part
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/rfc2045.txt (section 7)
Related information:
Specifies a Unique ID for one MIME body part of the content of a message.

2.1.41 Content-Description: header

Header name:
Content-Description
Description:
Description of message body part
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/rfc2045.txt (section 8)
Related information:
Description of a particular body part of a message, for example a caption for an image body part.

2.1.42 Content-Transfer-Encoding: header

Header name:
Content-Transfer-Encoding
Description:
Content transfer encoding applied
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/rfc2045.txt (section 6)
Related information:
Coding method used in a MIME message body part.

2.1.43 Content-Type: header

Header name:
Content-Type
Description:
MIME content type
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/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 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.

2.1.44 Disposition-Notification-To: header

Header name:
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.

2.1.45 Disposition-Notification-Options: header

Header name:
Disposition-Notification-Options
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.

2.1.46 Original-Recipient: header

Header name:
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.

2.1.47 Content-Base: header

Header name:
Content-Base
Description:
Base to be used for resolving relative URIs within this content part.
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/rfc2110.txt
Related information:
Base to be used for resolving relative URIs within this content part.

2.1.48 Content-Location: header

Header name:
Content-Location
Description:
URI for retrieving a body part
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/rfc2110.txt
Related information:
URI with which the content of this content part might be retrievable.

2.1.49 DL-Expansion-History: header

Header name:
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/rfc2822.txt
Related information:
Trace of distribution lists passed. (MIXER X.400 mapping, not for general use.)

2.1.50 Alternate-Recipient: header

Header name:
Alternate-Recipient
Description:
Controls forwarding to alternate 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/rfc2822.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.

2.1.51 Original-Encoded-Information-Types: header

Header name:
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/rfc2822.txt
Related information:
Which body part types occur in this message. RFC 2156 (MIXER), not for general use.

2.1.52 Content-Return: header

Header name:
Content-Return
Description:
Return content on non-delivery?
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
Related information:
Indicates whether the content of a message is to be returned with non-delivery notifications. RFC 2156 (MIXER), not for general use.

2.1.53 X400-Content-Return: header

Header name:
X400-Content-Return
Description:
Possible future name for 'Content-Return:'
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Possible future change of name for 'Content-Return:'.

2.1.54 Generate-Delivery-Report: header

Header name:
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/rfc2822.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.

2.1.55 Prevent-NonDelivery-Report: header

Header name:
Prevent-NonDelivery-Report
Description:
Non-delivery report required?
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
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.

2.1.56 Obsoletes: header

Header name:
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/rfc2822.txt
Related information:
Reference to a previous message being corrected and replaced. Compare to 'Supersedes:'. This field may in the future be replaced with 'Supersedes:'. RFC 2156, not for general use.

2.1.57 Content-Identifier: header

Header name:
Content-Identifier
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/rfc2822.txt
Related information:
A text string which identifies the content of a message. RFC 2156, not for general usage.

2.1.58 Delivery-Date: header

Header name:
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/rfc2822.txt
Related information:
The time when a message was delivered to its recipient. RFC 2156 (MIXER), not for general use.

2.1.59 Expiry-Date: header

Header name:
Expiry-Date
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/rfc2822.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.

2.1.60 Reply-By: header

Header name:
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/rfc2822.txt
Related information:
Latest time at which a reply is requested (not demanded). RFC 2156 (MIXER), not for general usage.

2.1.61 Importance: header

Header name:
Importance
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/rfc2822.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).

2.1.62 Incomplete-Copy: header

Header name:
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/rfc2822.txt
Related information:
Body parts are missing. RFC 2156 (MIXER), not for general usage.

2.1.63 Priority: header

Header name:
Priority
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/rfc2822.txt
Related information:
Can be 'normal', 'urgent' or 'non-urgent' and can influence transmission speed and delivery. RFC 2156 (MIXER), not for general use.

2.1.64 Sensitivity: header

Header name:
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/rfc2822.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).

2.1.65 Language: header

Header name:
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/rfc2822.txt
Related information:
Can include a code for the natural language used in a message, e.g. 'en' for English. RFC 2156 (MIXER), not for general usage.

2.1.66 Conversion: header

Header name:
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/rfc2822.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.

2.1.67 Conversion-With-Loss: header

Header name:
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/rfc2822.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.

2.1.68 Message-Type: header

Header name:
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/rfc2822.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.

2.1.69 Autoforwarded: header

Header name:
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/rfc2822.txt
Related information:
Has been automatically forwarded. RFC 2156 (MIXER), not for general usage.

2.1.70 Discarded-X400-IPMS-Extensions: header

Header name:
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/rfc2822.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.

2.1.71 Discarded-X400-MTS-Extensions: header

Header name:
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/rfc2822.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.

2.2 Provisional header registrations

Header name         Protocol  Description
-----------         --------  -----------
Message-Context     mail      Type or context of message
Apparently-To       mail      Envelope recipients inserted my
                              MTA
Approved-By         mail      Mailing list moderator who has
                              approved message
Fax                 mail      Fax number of the originator
Telefax             mail      Fax number of the originator
For-Approval        mail      Recipients for approval of this
                              message
For-Comment         mail      Recipients for comment on this
                              message
For-Handling        mail      Primary recipients for handling
                              this message
Mail-System-Version mail      Information about originating
                              client software
Mailer              mail      Information about originating
                              client software
Originating-Client  mail      Information about originating
                              client software
X-Mailer            mail      Information about originating
                              client software
X-Newsreader        mail      Information about originating
                              client software
X-MimeOLE           mail      Information about originating
                              client software
User-Agent          mail      Information about originating
                              client software
Originator-Info     mail      Originator authentication
                              information
Phone               mail      Phone number of the originator.
X-Envelope-From     mail      Mail envelope sender
Envelope-To         mail      Mail envelope recipient
X-Envelope-To       mail      Mail envelope recipient
X-Face              mail      Picture of the sender
X-RCPT-TO           mail      Mail envelope recipient
X-Sender            mail      Tentative message sender
X-X-Sender          mail      Extra-tentative message sender
Posted-To           mail      Nesgroup to which message was sent
X-Admin             mail      Submission server administrator
                              mailbox
Errors-To           mail      Address for notifications to be
                              sent
Return-Receipt-To   mail      Address for notifications to be
                              sent
Read-Receipt-To     mail      Address for notifications to be
                              sent
X-Confirm-reading-tomail      Address for notifications to be
                              sent
Return-Receipt-Requestedmail  Address for notifications to be
                              sent
Register-Mail-Reply-Requested-Bymail Address for notifications
                              to be sent
Abuse-Reports-To    mail      Mailbox for reporting abuse
X-Complaints-To     mail      Mailbox for reporting abuse
X-Report-Abuse-To   mail      Mailbox for reporting abuse
Content-Alias       mail      Alternatice to Content-Location
                              URI
Delivered-To        mail      Message loop detection
X-Loop              mail      Message loop detection
Translated-By       mail      Mailbox of translator
Translation-Of      mail      Reference source of translation
X-UIDL              mail      Message identifier within
                              mailstore
X-URI               mail      URI of body part content
X-URL               mail      Location of body part content
X-IMAP              mail      IMAP UID
X-OriginalArrivalTimemail     Time message was submitted
Precedence          mail      Message precedence indicator
X-MSMail-Priority   mail      Yet another priority indication.
X-Priority          mail      Message priority
Content-Length      mail      Size in bytes of body part
Content-Conversion  mail      Variant of 'Conversion:'
Content-Class       mail      Hierarchical content
                              classification
Content-SGML-Entity mail      SGML entity information
X-MIME-Autoconvertedmail      In-transit message conversion
                              information
List-Digest         mail      URL for mailing list digest
                              subscription
Mailing-List        mail      Mailing list information
X-Mailing-List      mail      Mailing list information
List-Software       mail      Mailing list software information
List-URL            mail      URL for mailing list information
X-Listserver        mail      List server software information
X-List-Host         mail      List server software information
Fcc                 mail      File for copy of message
Speech-Act          mail      Speech act categorization of
                              message
Status              mail      Message status in delivery system
X-No-Archive        mail      Do not archive publicly

2.2.1 Message-Context: header

Header name:
Message-Context
Description:
Type or context of message
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Can have the values 'voice-message', 'fax-message', 'pager-message', 'multimedia-message', 'text-message', 'none'

2.2.2 Apparently-To: header

Header name:
Apparently-To
Description:
Envelope recipients inserted my MTA
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
Non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Inserted by Sendmail when there is no 'To:' recipient in the original message, listing recipients derived from the envelope into the message heading. This behavior is not quite proper, MTAs should not modify headings (except inserting Received lines), and it can in some cases cause Bcc recipients to be wrongly divulged to non-Bcc recipients. Discouraged, mentioned in RFC 1211.

2.2.3 Approved-By: header

Header name:
Approved-By
Description:
Mailing list moderator who has approved message
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Name of the moderator of a mailing list, who has approved this message for distribution to the members of the list. Non-standard, used by some mailing list expansion systems.

2.2.4 Fax: header

Header name:
Fax
Description:
Fax number of the originator
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Fax number of the originator.

2.2.5 Telefax: header

Header name:
Telefax
Description:
Fax number of the originator
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Fax number of the originator.

2.2.6 For-Approval: header

Header name:
For-Approval
Description:
Recipients for approval of this message
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Primary recipients, who are requested to approve the information in this message or its attachments.

2.2.7 For-Comment: header

Header name:
For-Comment
Description:
Recipients for comment on this message
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Primary recipients, who are requested to comment on the information in this message or its attachments.

2.2.8 For-Handling: header

Header name:
For-Handling
Description:
Primary recipients for handling this message
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Primary recipients, who are requested to handle the information in this message or its attachments.

2.2.9 Mail-System-Version: header

Header name:
Mail-System-Version
Description:
Information about originating client software
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Information about the client software of the originator.

2.2.10 Mailer: header

Header name:
Mailer
Description:
Information about originating client software
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Information about the client software of the originator.

2.2.11 Originating-Client: header

Header name:
Originating-Client
Description:
Information about originating client software
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Information about the client software of the originator.

2.2.12 X-Mailer: header

Header name:
X-Mailer
Description:
Information about originating client software
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Information about the client software of the originator.

2.2.13 X-Newsreader: header

Header name:
X-Newsreader
Description:
Information about originating client software
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Information about the client software of the originator.

2.2.14 X-MimeOLE: header

Header name:
X-MimeOLE
Description:
Information about originating client software
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Information about the client software of the originator.

2.2.15 User-Agent: header

Header name:
User-Agent
Description:
Information about originating client software
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Information about the client software of the originator.

2.2.16 Originator-Info: header

Header name:
Originator-Info
Description:
Originator authentication information
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Contains information about the authentication of the originator in a format which is not easily used to send email to, to avoid the problems with 'Sender' and 'X-Sender'.

2.2.17 Phone: header

Header name:
Phone
Description:
Phone number of the originator.
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Phone number of the originator.

2.2.18 X-Envelope-From: header

Header name:
X-Envelope-From
Description:
Mail envelope sender
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
If the sender in the envelope (SMTP 'MAIL FROM') is not the same as the senders in the 'From' or 'Sender' header fields, some mail servers add this as an aid to clients which would otherwise not be able to display this information.

2.2.19 Envelope-To: header

Header name:
Envelope-To
Description:
Mail envelope recipient
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
If the recipient in the envelope (SMTP 'RCPT TO') is not included in the CC list, some mail servers add this header field as an aid to clients which would otherwise not be able to display the envelope recipients.

2.2.20 X-Envelope-To: header

Header name:
X-Envelope-To
Description:
Mail envelope recipient
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
If the recipient in the envelope (SMTP 'RCPT TO') is not included in the CC list, some mail servers add this header field as an aid to clients which would otherwise not be able to display the envelope recipients.

2.2.21 X-Face: header

Header name:
X-Face
Description:
Picture of the sender
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
48x48 bitmap with picture of the sender of this message.

2.2.22 X-RCPT-TO: header

Header name:
X-RCPT-TO
Description:
Mail envelope recipient
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Mail header field indication of the of the SMTP envelope recipient for this message.

2.2.23 X-Sender: header

Header name:
X-Sender
Description:
Tentative message sender
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Some mail software expect 'Sender:' to be an e-mail address which you can send mail to. However, some mail software has as the best authenticated sender a POP or IMAP account, which you might not be able to send to. Because of this, some mail software put the POP or IMAP account into an X-sender header field instead of a Sender header field, to indicate that you may not be able to send e-mail to this address. See also 'X-X-Sender'. Another use of 'X-Sender:' is that some e-mail software, which wants to insert a 'Sender:' header, will first change an existing 'Sender:' header to 'X-Sender'. This use is actually often the same as that described above, since the new 'Sender:' is added because it is better authenticated than the old value.

2.2.24 X-X-Sender: header

Header name:
X-X-Sender
Description:
Extra-tentative message sender
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Even though some systems put the POP or IMAP account name into the 'X-Sender:' instead of the Sender header field, some mail software tries to send to the 'X-Sender:' too. To stop this, some systems have begun to use 'X-X-Sender:' to indicate an authentication of the sender which might not be useable to send e-mail to. See also 'Originator-Info:'.

2.2.25 Posted-To: header

Header name:
Posted-To
Description:
Nesgroup to which message was sent
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
When a message is sent both to netnews and e-mail, this header is used in the e-mail version of the message to indicate which newsgroup it was sent to. This header thus contains the same information as the 'Newsgroups:' header in the netnews version of the message.

2.2.26 X-Admin: header

Header name:
X-Admin
Description:
Submission server administrator mailbox
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
E-mail address of administrator of a server, through which this message was submitted.

2.2.27 Errors-To: header

Header name:
Errors-To
Description:
Address for notifications to be sent
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Address to which notifications are to be sent and a request to get delivery notifications. Internet standards recommend, however, the use of MAIL FROM and Return-Path, not Errors-To, for where delivery notifications are to be sent. Non-standard, discouraged, may be widely used.

2.2.28 Return-Receipt-To: header

Header name:
Return-Receipt-To
Description:
Address for notifications to be sent
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Address to which notifications are to be sent and a request to get delivery notifications. Internet standards recommend, however, the use of MAIL FROM and Return-Path, not Errors-To, for where delivery notifications are to be sent. Non-standard, discouraged, may be widely used.

2.2.29 Read-Receipt-To: header

Header name:
Read-Receipt-To
Description:
Address for notifications to be sent
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Address to which notifications are to be sent and a request to get delivery notifications. Internet standards recommend, however, the use of MAIL FROM and Return-Path, not Errors-To, for where delivery notifications are to be sent. Non-standard, discouraged, may be widely used.

2.2.30 X-Confirm-reading-to: header

Header name:
X-Confirm-reading-to
Description:
Address for notifications to be sent
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Address to which notifications are to be sent and a request to get delivery notifications. Internet standards recommend, however, the use of MAIL FROM and Return-Path, not Errors-To, for where delivery notifications are to be sent. Non-standard, discouraged, may be widely used.

2.2.31 Return-Receipt-Requested: header

Header name:
Return-Receipt-Requested
Description:
Address for notifications to be sent
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Address to which notifications are to be sent and a request to get delivery notifications. Internet standards recommend, however, the use of MAIL FROM and Return-Path, not Errors-To, for where delivery notifications are to be sent. Non-standard, discouraged, may be widely used.

2.2.32 Register-Mail-Reply-Requested-By: header

Header name:
Register-Mail-Reply-Requested-By
Description:
Address for notifications to be sent
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Address to which notifications are to be sent and a request to get delivery notifications. Internet standards recommend, however, the use of MAIL FROM and Return-Path, not Errors-To, for where delivery notifications are to be sent. Non-standard, discouraged, may be widely used.

2.2.33 Abuse-Reports-To: header

Header name:
Abuse-Reports-To
Description:
Mailbox for reporting abuse
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Indicates where to send complaints if you get a message which you think is against the laws or rules.

2.2.34 X-Complaints-To: header

Header name:
X-Complaints-To
Description:
Mailbox for reporting abuse
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Indicates where to send complaints if you get a message which you think is against the laws or rules.

2.2.35 X-Report-Abuse-To: header

Header name:
X-Report-Abuse-To
Description:
Mailbox for reporting abuse
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Indicates where to send complaints if you get a message which you think is against the laws or rules.

2.2.36 Content-Alias: header

Header name:
Content-Alias
Description:
Alternatice to Content-Location URI
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Used in addition to Content-Location if this content part can be retrieved through more than one URI. Only one of them is allowed in the Content-Location, the other can be specified in Content-Alias.

2.2.37 Delivered-To: header

Header name:
Delivered-To
Description:
Message loop detection
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Used by some automatic services (mainly MLMs and autoresponders) for the purpose of loop detection. The service adds the Delivered-To header to outgoing messages, with its e-mail address as a value, and discards incoming messages which already have it.

2.2.38 X-Loop: header

Header name:
X-Loop
Description:
Message loop detection
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Used by some automatic services (mainly MLMs and autoresponders) for the purpose of loop detection. The service adds the Delivered-To header to outgoing messages, with its e-mail address as a value, and discards incoming messages which already have it.

2.2.39 Translated-By: header

Header name:
Translated-By
Description:
Mailbox of translator
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Mailbox of the person who made the translation.

2.2.40 Translation-Of: header

Header name:
Translation-Of
Description:
Reference source of translation
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Reference to the Message-ID of a message, of which the current message is a translation.

2.2.41 X-UIDL: header

Header name:
X-UIDL
Description:
Message identifier within mailstore
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Unique identifier for a message, local to a particular local mailbox store. The UIDL identifier is defined in the POP3 standard, but not the 'X-UIDL:' header.

2.2.42 X-URI: header

Header name:
X-URI
Description:
URI of body part content
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Similar usage as 'X-URL', but may indicate any URI, not just a URL.

2.2.43 X-URL: header

Header name:
X-URL
Description:
Location of body part content
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Sometimes used with the same meaning as 'Content-Location:', sometimes to indicate the web home page of the sender or of his organisation.

2.2.44 X-IMAP: header

Header name:
X-IMAP
Description:
IMAP UID
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
The UID, as defined in the IMAP standard. Only used in internal mailbox storage in some mail systems, should never be visible to a user.

2.2.45 X-OriginalArrivalTime: header

Header name:
X-OriginalArrivalTime
Description:
Time message was submitted
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Time when this message was delivered into the message transport system (usually the same time as in the last 'Received:' header)

2.2.46 Precedence: header

Header name:
Precedence
Description:
Message precedence indicator
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Sometimes used as a priority value which can influence transmission speed and delivery. Common values are 'bulk' and 'first-class'. Other uses is to control automatic replies and to control return-of-content facilities, and to stop mailing list loops. Non-standard, controversial, widely used.

2.2.47 X-MSMail-Priority: header

Header name:
X-MSMail-Priority
Description:
Yet another priority indication.
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Yet another priority indication.

2.2.48 X-Priority: header

Header name:
X-Priority
Description:
Message priority
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Values: 1 (Highest), 2 (High), 3 (Normal), 4 (Low), 5 (Lowest). 3 (Normal) is default if the field is omitted.

2.2.49 Content-Length: header

Header name:
Content-Length
Description:
Size in bytes of body part
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Inserted by certain mailers to indicate the size in bytes of the message text. This is part of a format some mailers use when showing a message to its users, and this header field should not be used when sending a message through the net. The use of this header field in transmission of a message can cause several robustness and interoperability problems.

2.2.50 Content-Conversion: header

Header name:
Content-Conversion
Description:
Variant of 'Conversion:'
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Non-standard variant of 'Conversion:' with the same values.

2.2.51 Content-Class: header

Header name:
Content-Class
Description:
Hierarchical content classification
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Type information of the content in some class hierarchy. Class hierarchies are commonly used to classify data structures in software development.

2.2.52 Content-SGML-Entity: header

Header name:
Content-SGML-Entity
Description:
SGML entity information
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Information from the SGML entity declaration corresponding to the entity contained in the body of the body part.

2.2.53 X-MIME-Autoconverted: header

Header name:
X-MIME-Autoconverted
Description:
In-transit message conversion information
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Information about conversion of this message on the path from sender to recipient, such as conversion between MIME encoding formats.

2.2.54 List-Digest: header

Header name:
List-Digest
Description:
URL for mailing list digest subscription
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
URL to use to get a subscription to the digest version of a mailing list from which this message was relayed.

2.2.55 Mailing-List: header

Header name:
Mailing-List
Description:
Mailing list information
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Non-standard precursors to List-ID and List-Post.

2.2.56 X-Mailing-List: header

Header name:
X-Mailing-List
Description:
Mailing list information
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Non-standard precursors to List-ID and List-Post.

2.2.57 List-Software: header

Header name:
List-Software
Description:
Mailing list software information
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Information about the software used in a mailing list expander through which this message has passed. Non-standard, has been considered for inclusion in RFC2369.

2.2.58 List-URL: header

Header name:
List-URL
Description:
URL for mailing list information
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Contains URL where information of various kinds about the mailing list from which this message was relayed.

2.2.59 X-Listserver: header

Header name:
X-Listserver
Description:
List server software information
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Information about the server and software used in a mailing list expander through which this message has passed. Warning: 'Listserv' is a trademark and should not be used for other than the 'Listserv' product. Use, instead the 'List-Software' header field. Non-standard. Recommended to use 'List-Software' instead.

2.2.60 X-List-Host: header

Header name:
X-List-Host
Description:
List server software information
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Information about the server and software used in a mailing list expander through which this message has passed. Warning: 'Listserv' is a trademark and should not be used for other than the 'Listserv' product. Use, instead the 'List-Software' header field. Non-standard. Recommended to use 'List-Software' instead.

2.2.61 Fcc: header

Header name:
Fcc
Description:
File for copy of message
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Name of file in which a copy of this message is stored.

2.2.62 Speech-Act: header

Header name:
Speech-Act
Description:
Speech act categorization of message
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Speech act categoriztion of a message. Examples of speech acts are Question, Idea, More, Promise, Sad, Happy, Angry, Summary, Decision.

2.2.63 Status: header

Header name:
Status
Description:
Message status in delivery system
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
This field is used by some mail delivery systems to indicate the status of delivery for this message when stored. Common values of this field are: U message is not downloaded and not deleted. R message is read or downloaded. O message is old but not deleted. D to be deleted. N new (a new message also sometimes is distinguished by not having any 'Status:' header field. Combinations of these characters can occur, such as 'Status: OR' to indicate that a message is downloaded but not deleted. Non-standard, should never appear in mail in transit.

2.2.64 X-No-Archive: header

Header name:
X-No-Archive
Description:
Do not archive publicly
Applicable protocol:
mail (http://www.rfc-editor.org/rfc/rfc2822.txt)
Status:
non-standard
Author/change controller:
Unknown (mailto:xxxx@ietf.org).
Specification document(s):
http://www.ietf.org/internet-drafts/draft-palme-mailext-headers-06.txt
Related information:
Do not archive this message in publicly available archives.


 TOC 

3. IANA considerations

This specification provides an initial registration of mail headers in the two registries defined by Registration procedures for message headers[1]:


 TOC 

4. Security considerations

No security considerations are introduced by this specification beyond those already inherent in the use of message headers.


 TOC 

5. Acknowledgements

Most of the information in this document has been derived from Jacob Palme's work in RFC 2076[8] and subsequent updates [20].

The author also gratefully acknowledges the contribution of: Mark Nottingham, [[[...]]]


 TOC 

References

[1] Klyne, G., Nottingham, M. and J. Mogul, "Registration procedures for message headers", Mar 2002.
[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] Moore, K., Troost, R. and S. Dorner, "Communicating 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] Baer, J. and G. Neufeld, "The Use of URLs as Meta-Syntax for Core Mail List Commands and their Transport through Message Header Fields", RFC 2369, July 1998.
[15] Parsons, G. and G. Vaudreuil, "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, April 2001.
[20] Palme, J., "Common Internet Message Header Fields", Internet draft draft-palme-mailext-headers-06, November 2001.
 TOC 

Author's Address

  Graham Klyne
  Clearswift Corporation
  MIMEsweeper Group
  1310 Waterside
  Arlington Business Park
  Theale, Reading RG7 4SA
  UK
Phone:  +44 11 8903 8903
EMail:  Graham.Klyne@MIMEsweeper.com
 TOC 

Appendix A. Revision history

[[[Please remove this section on final publication]]]

A.1 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.


 TOC 

Appendix B. TODO:

[[[Please remove this section on final publication]]]


 TOC 

Full Copyright Statement

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