Network Working Group J. Palme
Internet Draft Stockholm University/KTH
<draft-ietf-mailext-mail-attributes-00.txt> Sweden
Category: Informational March 1995
Expires September 1995
Common Internet Message Attributes
1. Status of this Memo
This document is an Internet-Draft. 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.''
To learn the current status of any Internet-Draft, please check
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ds.internic.net (US East Coast), or ftp.isi.edu (US West Coast).
This memo provides information for the Internet community. This
memo does not specify an Internet standard of any kind, since
this document is mainly a compilation of information taken from
other RFC-s.. Distribution of this memo is unlimited.
2. Abstract
This memo contains a table of commonly occurring attributes in
headings and on envelopes of e-mail messages. The document compiles
information from other RFC-s such as RFC 821, RFC 822, RFC 1036,
RFC 1327, RFC 1496, RFC 1521 and X.400. A few commonly occurring
attributes which are not defined in RFC-s are also included. For
each attribute, the memo gives a short description and a reference
to the RFC or X.400 part, in which the attribute is defined.
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Internet draft Common Internet Message Attributes March 1995
3. Table of contents
4. Introduction
5. Use of gatewaying attributes
6. Table of attributes
6.1 Addressing information
6.2 Envelope and format information
6.3 Header fields containing mailbox names and addressable entities
6.4 Message identification and referral attributes
6.5 Other textual attributes
6.6 Attributes containing dates and times
6.7 Attributes containing other types of information
6.8 Resent-attributes
6.9 Sometimes occurring heading fields in Internet mail
which are not according to standard
7. Acknowledgments
8. References
9. Author's address
Appendix A: Attributes sorted by Internet RFC document in which
they appear
4. Introduction
Many different Internet standards and RFC-s define attributes which
may occur on Internet Mail Messages and Network News Articles. The
intention of this document is to list all such attributes in one
document as an aid to people developing message systems or interested
in Internet Mail standards.
The document contains all heading attributes which the author has
found in the following Internet standards: RFC 821 [1], RFC 822 [2],
RFC 1036 [3], RFC 1327 [4], RFC 1496 [5] and RFC 1521 [6]. Note in
particular that heading attributes defined in RFC 1421-1424, Privacy
Enhancement for Internet Electronic Mail, are not included. A few
additional attributes which often can be found in e-mail headings
are also included.
For each heading attribute, the document gives a short description and
a reference to the Internet standard or RFC, in which they are defined.
Information about corresponding attributes in X.400 is also given
when available.
5. Use of gatewaying attributes
RFC 1327 defines a number of new attributes in Internet mail, which
are defined to map attributes which X.400 have but which were
previously not standardized in Internet mail. Some of these attributes
are obviously useful also as stand-alone Internet mail message
attributes. The fact that an attribute occurs in RFC 1327 indicates
that it is recommended for use in gatewaying messages between X.400
and Internet mail, but does not necessarily mean that the attribute
is recommended for messages wholly within Internet mail. However, some
of these attributes may eventually get accepted also for usage within
Internet mail.
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Internet draft Common Internet Message Attributes March 1995
Fields are given here in the spelling used in e-mail headers. This
may sometimes be English, sometimes American spelling. One attribute,
"Organisation/Organization" occurs in e-mail headers sometimes with
English, sometimes with American spelling.
6. Table of attributes
6.1 Addressing information
Description Internet att- Internet X.400 X400
ribute name document attribute document
-----------------------+-------------+------------+------------+-------+
Original sender. Should MAIL FROM RFC 821 Originator X.411
in Internet be empty name
when sending
notifications, and be
the list administrator
when forwarding from a
distribution list.
Relative address to the Return-Path: RFC 821 Trace X.411
original sender along
the reverse path
through which the
message was sent
Recipient to which RCPT TO RFC 821 Recipient X.411
message is to be name
delivered.
6.2 Envelope and format information
Description Internet att- Internet X.400 X400
ribute name document attribute document
-----------------------+-------------+------------+------------+-------+
All that is inside the DATA RFC 821 Content X.411
envelope.
Trace of MTA-s which a Received: RFC 822: Trace X.411
message has passed. 4.3.2
MIME protocol version MIME-Version: RFC 1521: 3 Mapped into RFC
body part 1496
Format of content Content-Type: RFC 1521: 4 Mapped into RFC
(character set etc.) body part 1496
Coding method used in Content- RFC 1521: 5
content. Transfer-
Encoding
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Internet draft Common Internet Message Attributes March 1995
Description Internet att- Internet X.400 X400
ribute name document attribute document
-----------------------+-------------+------------+------------+-------+
List of MTA-s passed. Path: RFC 1036: Trace X.411
2.1.6
Special Usenet News Control: RFC 1036:
actions. 2.2.6
Trace of distribution DL-Expansion- RFC 1327 DL Expansion X.411
lists passed. history- History
indication indication
Which body part types Original- RFC 1327 Original- X.411
occur in this message. Encoded- encoded-
Information- information-
Types: types
Special informational Message-Type: RFC 1327 Notification X.411
message. Delivery Report
Controls whether this Alternate- RFC 1327 Alternate- X.411
message may be recipient: recipient-
forwarded to a allowed
postmaster if delivery
is not possible to the
intended recipient.
Default: Allowed.
Whether non-delivery Prevent- RFC 1327 Originator X.411
report is wanted at NonDelivery- ReportRequest
delivery error. Default Report:
is to want such a
report.
Whether a delivery Generate- RFC 1327 Originator X.411
report is wanted at Delivery- ReportRequest
successful delivery. Report:
Default is not to
generate such a report.
Whether recipients are Disclose- RFC 1327 Disclosure- X.411
to be told the names of Recipients: of-recipients
other recipients of the
same message. This is
primarily an X.400
facility, such
disclosure is in
Internet mail done via
the To:, Cc: and Bcc:
heading fields.
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Internet draft Common Internet Message Attributes March 1995
Indicates whether the Content- RFC 1327 Content-return- X.411
content of a message is Return request
to be returned with
non-delivery
notifications.
6.3 Header fields containing mailbox names and addressable entitities
Description Internet att- Internet X.400 X400
ribute name document attribute document
-----------------------+-------------+------------+------------+-------+
Replacement for "From:" Reply-To: RFC 822: Reply- X.420
to which replies are to 4.4.3 recipients
be sent.
Author, approver. From: RFC 822: Authorizing- X.420
4.4.1 users
Moderator. Approved: RFC 1036: Authorizing- X.420
2.2.11 users
Sender information Sender: RFC 822: Originator X.420
inside the envelope. 4.4.2
Main recipients. To: RFC 822: Primary- X.420
4.5.1 recipients
Additional recipients. Cc: RFC 822: Copy- X.420
4.5.2 recipients
Recipients not shown to Bcc: RFC 822: Blind-copy- X.420
other recipients. 4.5.3 recipients
In Usenet News: group Newsgroups: RFC 1036: Primary- X.420
to which this article 2.1.3 Recipient
was posted. In e-mail:
either group to which
this message was posted
or group to which the
article this message is
a reply-to was posted.
Where group replies to Followup-To: RFC 1036:
this message are to be 2.2.3
sent.
Limitation on where Distribution: RFC 1036:
this message can be 2.2.7
distributed.
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6.4 Message identification and referral attributes
Description Internet att- Internet X.400 X400
ribute name document attribute document
-----------------------+-------------+------------+------------+-------+
Unique ID of this Message-ID: RFC 822: IPM X.420
message. 4.6.1 Identifier
Unique ID of one body Content-ID: RFC 1521: not
part of the content of 6.1 available
a message.
Reference to message In-Reply-To: RFC 822: Replied-to- X.420
which this message is a 4.6.2 IPM
reply to.
Reference to other References: RFC 822: Related-IPMs X.420
related messages. 4.6.3
Reference to previous Obsoletes: RFC 1327 Obsoleting X.420
message being corrected
and replaced.
6.5 Other textual attributes
Description Internet att- Internet X.400 X400
ribute name document attribute document
-----------------------+-------------+------------+------------+-------+
Search keys for data Keywords: RFC 822: Heading RFC 1327
base retrieval. 4.6.4 extension
Title, heading, Subject: RFC 822: Subject X.420
subject. 4.7.1
Comments on a message. Comments: RFC 822: Extra body X.420
4.7.2 part
Description of a Content- RFC 1521: Heading RFC 1327
particular body part description: 6.2 extension
of a message.
Organisation to which Organization: RFC 1036: organization- X.520
the sender of this 2.2.8 name
message belongs.
Short text describing Summary: RFC 1036: Heading RFC 1327
a longer message. 2.2.10 extension???
A text string which Content- RFC 1327 Content- X.411
identifies the content identifier: identifier
of a message.
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6.6 Attributes containing dates and times
Description Internet att- Internet X.400 X400
ribute name document attribute document
-----------------------+-------------+------------+------------+-------+
The time when a Delivery- RFC 1327 Message- X.411
message was delivered Date: delivery
to its recipient. time
In Internet, the date Date: RFC 822: Message- X.411
when a message was 5.1 submission-
written, in X.400, the time
time a message was
submitted.
A suggested expiration Expires: RFC 1036: Expiry Date X.420
date. Can be used both 2.2.4 Indication
to limit the time of an
article which is not
meaningful after a
certain date, and to
extend the storage of
important articles.
Time at which a message Expiry-Date: RFC 1327 Expiry Date X.420
loses its validity. Indication
Latest time at which a Reply-By: RFC 1327 ReplyTime X.420
reply is requested (not Field
demanded).
6.7 Attributes containing other types of information
Description Internet att- Internet X.400 X400
ribute name document attribute document
-----------------------+-------------+------------+------------+-------+
Can be normal, urgent Priority: RFC 1327 Priority X.411
or non-urgent and can
influence transmission
speed and delivery.
Size of the message. Lines: RFC 1036: Heading RFC 1327
2.2.12 extension???
Has been automatically Auto- RFC 1327 Auto- X.420
forwarded. Forwarded: Forwarded
Indication
Can be high, normal or Importance: RFC 1327 Importance X.420
low and is only used in
the recipient client
(UA).
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Internet draft Common Internet Message Attributes March 1995
Description Internet att- Internet X.400 X400
ribute name document attribute document
-----------------------+-------------+------------+------------+-------+
Body parts are missing. Incomplete- RFC 1327 Incomplete X.420
Copy: Copy
Can include a two- Language: RFC 1327 Language X.420
character code for the
natural language used
in a message, e.g. "en"
for English.
Can be personal, Sensitivity: RFC 1327 Sensitivity X.420
private, company-
confidential or
absent.
The body of this mess- Conversion: RFC 1327 Implicit- X.411
age may not be conver- conversion-
ted from one charac- prohibited
ter set to another.
The body of this Conversion- RFC 1327 Conversion- X.411
message may not be With-Loss: with-loss-
converted from one prohibited
character set to
another if information
will be lost.
Can be used in Internet Discarded- RFC 1327 Extensions X.420
mail to indicate X.400 X400-IPMS- Field
extensions which Extensions:
could not be mapped
to Internet mail Discarded- RFC 1327 Extensions X.420
format. X400-MTS- Field
Extensions:
6.8 Resent-attributes
Description Internet att- Internet X.400 X400
ribute name document attribute document
-----------------------+-------------+------------+------------+-------+
When forwarding a Resent-Reply- RFC 822, Embedded X.420
message, attributes To:, Resent- C.3.3 message
referring to the From:, Resent- bodies
forwarding, not to the Sender:, should be
original message. Resent-From:, used for
Resent-Date:, forwarding.
Note: MIME specifies Resent-To:,
another way of resen- Resent-cc:,
ding messages, using Resent-bcc:,
the "Message" Content- Resent-
Type. Message-ID:
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6.9 Sometimes occurring heading fields in Internet mail
which are not according to standard
This chapter does not include a complete collection of all heading
attributes, such a list would be much longer. It contains a few
attributes which occur frequently and for which an explanation may be
useful here.
Description Internet att- Internet X.400 X400
ribute name document attribute document
-----------------------+-------------+------------+------------+-------+
Inserted by Sendmail Apparently- RFC 1211
in certain cases, lis- to:
ting recipients deriv-
ed from the envelope
into the message
heading. This behavi-
or is not quite pro-
per, MTA-s should not
modify headings (ex-
cept inserting Reci-
eved lines), and it
can in some cases
cause Bcc recipients
to be wrongly divulged.
Inserted by certain Content-
mailers to indicate length:
the size in bytes of
the message text. Can
cause several robust-
ness and interoperabi-
lity problems and is
not recommended.
Pre-MIME way of indi- Encoding: RFC 1154
cating encoding format
in message.
Address to which Errors-To:,
notifications are to Return-
be sent. Internet Receipt-To:
standards recommend,
however, the use of
RCPT TO and Return-
Path, not Errors-To,
for this.
Fax number of the Fax:, X.520
originator. Telefax:
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Description Internet att- Internet X.400 X400
ribute name document attribute document
-----------------------+-------------+------------+------------+-------+
Name of file in which a Fcc:
copy of this message is
stored.
Information about the Mail-System-
client software of the Version:,
originator. Mailer:
See Organization. Organisation: organization X.520
-name
Information about the Originating-
client software of the Client:
originator.
Phone number of the Phone: O/R X.420
originator. Descriptor, X.520??
telephone-
number
Used in Usenet News Supersedes:
in similar ways to
the "Obsoletes" attri-
bute described earlier
in this document.
7. Acknowledgments
Harald Tveit Alvestrand and several other people has helped me with
compiling this list. I alone take responsibility for any errors which
may be in the list.
An earlier version of this list has been published as part of [7].
8. References
[1] J. Postel: "Simple Mail Transfer Protocol", STD 10, RFC 821,
August 1982.
[2] D. Crocker: "Standard for the format of ARPA Internet text
messages." STD 11, RFC 822, August 1982.
[3] M.R. Horton, R. Adams: "Standard for interchange of USENET
messages", RFC 1036, December 1987.
[4] S. Hardcastle-Kille: "Mapping between X.400(1988) / ISO 10021
and RFC 822", RFC 1327 May 1992.
[5] H. Alvestrand & 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.
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[6] 1521 N. Borenstein & N. Freed: "MIME (Multipurpose Internet
Mail Extensions) Part One: Mechanisms for Specifying and
Describing the Format of Internet Message Bodies",
RFC 1521, September 1993.
[7] J. Palme: "Electronic Mail", Artech House publishers, London-
Boston January 1995.
9. Author's address
Jacob Palme Phone: +46-8-16 16 67
Stockholm University/KTH Fax: +46-8-703 90 25 (not fast)
Electrum 230 E-mail: jpalme@dsv.su.se
S-164 40 Kista, Sweden
Appendix A:
Attributes sorted by Internet RFC document in which they appear.
RFC 821
-------
DATA
MAIL FROM
RCPT TO
RFC 822
-------
Bcc
Cc
Comments
Date
From
In-Reply-To
Keywords
Message-ID
Received
References
Reply-To
Resent-
Resent-bcc
Resent-Date
Resent-From
Resent-From
Resent-Message-ID
Resent-Reply-To
Resent-ToResent-cc
Return-Path
Sender
Sender
Subject
To
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RFC 1036
--------
Approved
Control
Distribution
Expires
Followup-To
Lines
Newsgroups
Organization
Path
Summary
RFC 1327
--------
Alternate-recipient
Auto-Forwarded
Autoforwarded
Content-identifier
Content-Return
Conversion
Delivery-Date
Discarded-X400-IPMS-Extensions
Discarded-X400-MTS-Extensions
Disclose-Recipients
DL-Expansion-History
Donversion-With-Loss
Expiry-Date
Generate-Delivery-Report
Importance
Incomplete-Copy
Language
Message-Type Delivery
Obsoletes
Original-Encoded-Information-Types
Prevent-NonDelivery-Report
Priority
Reply-By
Report
Sensitivity
RFC 1521
--------
Content-description
Content-ID
Content-Transfer-Encoding
Content-Type
MIME-Version
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Not Internet standard
---------------------
Apparently-to
Content-length
Encoding
Errors-To
Fax
Fcc
Mail-System-Version
Mailer
Organisation
Originating-Client
Phone
Return-Receipt-To
Supersedes
Telefax
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