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Versions: 00 01 02 03 04 05 06 RFC 2076

Network Working Group                                       Jacob Palme
Internet Draft                                 Stockholm University/KTH
draft-ietf-mailext-mail-attributes-06.txt                        Sweden
Category: Informational                                    October 1996
Expires March 1997





                  Common Internet Message Headers

                        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
  the ``1id-abstracts.txt'' listing contained in the Internet-
  Drafts Shadow Directories on ftp.is.co.za (Africa),
  nic.nordu.net (Europe), munnari.oz.au (Pacific Rim),
  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 RFCs.. Distribution of this memo is unlimited.



                            Abstract

This memo contains a table of commonly occurring headers in headings of
e-mail messages. The document compiles information from other RFCs such
as RFC 822, RFC 1036, RFC 1123, RFC 1327, RFC 1496, RFC 1521, RFC 1766,
RFC 1806, RFC 1864 and RFC 1911. A few commonly occurring headers
which are not defined in RFCs are also included. For each header, the
memo gives a short description and a reference to the RFC in which the
header is defined.








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                         Table of contents

1. Introduction
2. Use of gatewaying headers
3. Table of headers
     3.1 Phrases used in the tables
     3.2 Trace information
     3.3 Format and control information
     3.4 Sender and recipient indication
     3.5 Response control
     3.6 Message identification and referral headers
     3.7 Other textual headers
     3.8 Headers containing dates and times
     3.9 Quality information
     3.10 Language information
     3.11 Size information
     3.12 Conversion control
     3.13 Encoding information
     3.14 Resent-headers
     3.15 Security and reliability
     3.16 Miscellaneous
4. Acknowledgments
5. References
6. Author's address
Appendix A: Headers sorted by Internet RFC document in which
they appear.
Appendix B:                          Alphabetical index



                         1. Introduction

Many different Internet standards and RFCs define headers which
may occur on Internet Mail Messages and Usenet News Articles. The
intention of this document is to list all such headers in one
document as an aid to people developing message systems or interested
in Internet Mail standards.

The document contains all headers which the author has
found in the following Internet standards: , RFC 822 [2],
RFC 1036 [3], RFC 1123 [5], RFC 1327 [7], RFC 1496 [8], RFC 1521 [11],
RFC 1766 [12], RFC 1806 [14], RFC 1864[17] and RFC 1911[20]. Note in
particular that heading attributes defined in PEM (RFC 1421-1424) and
MOSS (RFC 1848 [16]) are not included. PEM and MOSS headers only appear
inside the body of a message, and thus are not headers in the RFC 822
sense. Mail attributes in envelopes, i.e. attributes controlling the
message transport mechanism between mail and news servers, are not
included. This means that attributes from SMTP [1], UUCP [18] and NNTP
[15] are mainly not covered either. Headings used only in HTTP [19] are
not included yet, but may be included in future version of this memo. A
few additional headers which often can be found in e-mail headings but
are not part of any Internet standard are also included.

For each header, the document gives a short description and
a reference to the Internet standard or RFC, in which they are defined.

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The header names given here are spelled the same way as when they are
actually used. This is usually American but sometimes English spelling.
One header in particular, "Organisation/Organization", occurs in e-mail
headers sometimes with the English and other times with the American
spelling.

The following words are used in this memo with the meaning specified
below:

heading           Formatted text at the top of a message, ended by a
                  blank line

header = heading  One field in the heading, beginning with a field
field             name, colon, and followed by the field value(s)

It is my intention to continue updating this document after its
publication as an RFC. The latest version, which may be more up-to-date
(but also less fully checked out) will be kept available for
downloading from URL
http://www.dsv.su.se/~jpalme/ietf-mail-attributes.pdf.

Please e-mail me (Jacob Palme <jpalme@dsv.su.se>) if you have noted
headers which should be included in this memo but are not.


                 2. Use of gatewaying headers

RFC 1327 defines a number of new headers in Internet mail, which are
defined to map headers which X.400 has but which were previously not
standardized in Internet mail. The fact that a header occurs in RFC
1327 indicates that it is recommended for use in gatewaying messages
between X.400 and Internet mail, but does not mean that the header is
recommended for messages wholly within Internet mail. Some of these
headers may eventually see widespread implementation and use in
Internet mail, but at the time of this writing (1996) they are not
widely implemented or used.

Headers defined only in RFC 1036 for use in Usenet News sometimes
appear in mail messages, either because the messages have been
gatewayed from Usenet News to e-mail, or because the messages were
written in combined clients supporting both e-mail and Usenet News in
the same client. These headers are not standardized for use in Internet
e-mail and should be handled with caution by e-mail agents.












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                      3. Table of headers

3.1 Phrases used in the tables


"not for general        Used to mark headers which are defined in RFC
usage"                  1327 for use in messages from or to Internet
                        mail/X.400 gateways. These headers have not
                        been standardized for general usage in the
                        exchange of messages between Internet mail-
                        based systems.

"not standardized       Used to mark headers defined only in RFC 1036
for use in e-mail"      for use in Usenet News. These headers have no
                        standard meaning when appearing in e-mail,
                        some of them may even be used in different
                        ways by different software. When appearing in
                        e-mail, they should be handled with caution.
                        Note that RFC 1036, although generally used as
                        a de-facto standard for Usenet News, is not an
                        official IETF standard or even on the IETF
                        standards track.

"non-standard"          This header is not specified in any of
                        referenced RFCs which define Internet
                        protocols, including Internet Standards, draft
                        standards or proposed standards. The header
                        appears here because it often appears in e-
                        mail or Usenet News. Usage of these headers is
                        not in general recommended. Some header
                        proposed in ongoing IETF standards development
                        work, but not yet accepted, are also marked in
                        this way.

"discouraged"           This header, which is non-standard, is known
                        to create problems and should not be
                        generated. Handling of such headers in
                        incoming mail should be done with great
                        caution.

"controversial"         The meaning and usage of this header is
                        controversial, i.e. different implementors
                        have chosen to implement the header in
                        different ways. Because of this, such headers
                        should be handled with caution and
                        understanding of the different possible
                        interpretations.








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"experimental"          This header is used for newly defined headers,
                        which are to be tried out before entering the
                        IETF standards track. These should only be
                        used if both communicating parties agree on
                        using them. In practice, some experimental
                        protocols become de-facto-standards before
                        they are made into IETF standards.



3.2 Trace information

Used to convey the information       Return-Path:    RFC 821,
from the MAIL FROM envelope                          RFC 1123: 5.2.13.
attribute in final delivery, when
the message leaves the SMTP
environment in which "MAIL FROM"
is used.

Trace of MTAs which a message has    Received:       RFC 822: 4.3.2,
passed.                                              RFC 1123: 5.2.8.

List of MTAs passed.                 Path:           RFC 1036: 2.2.6,
                                                     only in Usenet
                                                     News, not in e-
                                                     mail.

Trace of distribution lists          DL-Expansion-   RFC 1327, not for
passed.                              History-        general usage.
                                     Indication:

3.3 Format and control
information

An indicator that this message is    MIME-Version:   RFC 1521: 3.
formatted according to the MIME
standard, and an indication of
which version of MIME is
utilized.

Special Usenet News actions only.    Control:        RFC 1036: 2.1.6,
                                                     only in Usenet
                                                     News, not in e-
                                                     mail.

Special Usenet News actions and a    Also-Control:   son-of-RFC1036
normal article at the same time.                     [21], non-
                                                     standard, only in
                                                     Usenet News, not
                                                     in e-mail





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Which body part types occur in       Original-       RFC 1327, not for
this message.                        Encoded-        general usage.
                                     Information-
                                     Types:

Controls whether this message may    Alternate-      RFC 1327, not for
be forwarded to alternate            Recipient:      general usage.
recipients such as a postmaster
if delivery is not possible to
the intended recipient. Default:
Allowed.

Whether recipients are to be told    Disclose-       RFC 1327, not for
the names of other recipients of     Recipients:     general usage.
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: headers.

Whether a MIME body part is to be    Content-        RFC 1806,
shown inline or is an attachment;    Disposition:    experimental
can also indicate a suggested
filename for use when saving an
attachment to a file.

3.4 Sender and recipient
indication

Authors or persons taking            From:           RFC 822: 4.4.1,
responsibility for the message.                      RFC 1123: 5.2.15-
                                                     16, 5.3.7,
Note difference from the "From "                     RFC 1036 2.1.1
header (not followed by ":")
below.


(1) This header should never         From            not standardized
appear in e-mail being sent, and                     for use in e-mail
should thus not appear in this
memo. It is however included,
since people often ask about it.

This header is used in the so-
called Unix mailbox format, also
known as Berkely mailbox format
or the MBOX format. This is a
format for storing a set of
messages in a file. A line


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beginning with "From " is used to
separate successive messages in
such files.

This header will thus appear when
you use a text editor to look at
a file in the Unix mailbox
format. Some mailers also use
this format when printing
messages on paper.

The information in this header
should NOT be used to find an
address to which replies to a
message are to be sent.

(2) Used in Usenet News mail         From            RFC 976: 2.4 for
transport, to indicate the path      or              use in Usenet News
through which an article has gone    >From
when transferred to a new host.

Sometimes called "From_" header.

Name of the moderator of the         Approved:       RFC 1036: 2.2.11,
newsgroup to which this article                      not standardized
is sent; necessary on an article                     for use in e-mail.
sent to a moderated newsgroup to
allow its distribution to the
newsgroup members. Also used on
certain control messages, which
are only performed if they are
marked as Approved.

The person or agent submitting       Sender:         RFC 822: 4.4.2,
the message to the network, if                       RFC 1123: 5.2.15-
other than shown by the From:                        16, 5.3.7.
header.

Primary recipients.                  To:             RFC 822: 4.5.1,
                                                     RFC 1123: 5.2.15-
                                                     16, 5.3.7.

Secondary, informational             cc:             RFC 822: 4.5.2,
recipients. (cc = Carbon Copy)                       RFC 1123. 5.2.15-
                                                     16, 5.3.7.

Recipients not to be disclosed to    bcc:            RFC 822: 4.5.3,
other recipients. (bcc = Blind                       RFC 1123: 5.2.15-
Carbon Copy).                                        16, 5.3.7.






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In Usenet News: group(s) to which    Newsgroups:     RFC 1036: 2.1.3,
this article was posted.                             not standardized
Some systems provide this header                     and controversial
also in e-mail although it is not                    for use in e-mail.
standardized there.

Unfortunately, the header can
appear in e-mail with two
different and contradictory
meanings:

(a) Indicating the newsgroup
recipient of an article/message
sent to both e-mail and Usenet
News recipients.

(b) In a personally addressed
reply to an article in a news-
group, indicating the newsgroup
in which this discussion
originated.

Inserted by Sendmail when there      Apparently-     Non-standard,
is no "To:" recipient in the         To:             discouraged,
original message, listing                            mentioned in
recipients derived from the                          RFC 1211.
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.

Geographical or organizational       Distribution:   RFC 1036: 2.2.7,
limitation on where this article                     not standardized
can be distributed.                                  for use in e-mail.

Fax number of the originator.        Fax:,           Non-standard.
                                     Telefax:

Phone number of the originator.      Phone:          Non-standard.

Information about the client         Mail-System-    Non-standard.
software of the originator.          Version:,
                                     Mailer:,
                                     Originating-
                                     Client:, X-
                                     Mailer, X-
                                     Newsreader




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3.5 Response control

This header is meant to indicate     Reply-To:       RFC 822: 4.4.3,
where the sender wants replies to                    RFC 1036: 2.2.1
go. Unfortunately, this is                           controversial.
ambiguous, since there are
different kinds of replies, which
the sender may wish to go to
different addresses. In
particular, there are personal
replies intended for only one
person, and group replies,
intended for the whole group of
people who read the replied-to
message (often a mailing list,
anewsgroup name cannot appear
here because of different syntax,
see "Followup-To" below.).

Some mail systems use this header
to indicate a better form of the
e-mail address of the sender.
Some mailing list expanders puts
the name of the list in this
header. These practices are
controversial. The personal
opinion of the author of this RFC
is that this header should be
avoided except in special cases,
but this is a personal opinion
not shared by all specialists in
the area.

Used in Usenet News to indicate      Followup-To:    RFC 1036: 2.2.3,
that future discussions (=follow-                    not standardized
up) on an article should go to a                     for use in e-mail.
different set of newsgroups than
the replied-to article. The most
common usage is when an article
is posted to several newsgroups,
and further discussions is to
take place in only one of them.

In e-mail, this header may occur
in a message which is sent to
both e-mail and Usenet News, to
show where follow-up in Usenet
news is wanted. The header does
not say anything about where
follow-up in e-mail is to be
sent.

Note that the value of this
header must always be one or more
newsgroup names, never e-mail
addresses.

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Address to which notifications       Errors-To:,     Non-standard,
are to be sent and a request to      Return-         discouraged.
get delivery notifications.          Receipt-To:
Internet standards recommend,
however, the use of RCPT TO and
Return-Path, not Errors-To, for
where delivery notifications are
to be sent.

Whether non-delivery report is       Prevent-        RFC 1327, not for
wanted at delivery error. Default    NonDelivery-    general usage.
is to want such a report.            Report:

Whether a delivery report is         Generate-       RFC 1327, not for
wanted at successful delivery.       Delivery-       general usage.
Default is not to generate such a    Report:
report.

Indicates whether the content of     Content-        RFC 1327, not for
a message is to be returned with     Return:         general usage.
non-delivery notifications.

Possible future change of name       X400-Content-   non-standard
for "Content-Return:"                Return:

3.6 Message identification and
referral headers

Unique ID of this message.           Message-ID:     RFC 822: 4.6.1
                                                     RFC 1036: 2.1.5.

Unique ID of one body part of the    Content-ID:     RFC 1521: 6.1.
content of a message.

Base to be used for resolving        Content-Base:   Non-standard
relative URIs within this content
part.

URI with which the content of        Content-        Non-standard
this content part might be           Location:
retrievable.

Reference to message which this      In-Reply-To:    RFC 822: 4.6.2.
message is a reply to.

In e-mail: reference to other        References:     RFC 822: 4.6.3
related messages, in Usenet News:                    RFC 1036: 2.1.5.
reference to replied-to-articles.

References to other related          See-Also:       Son-of-RFC1036
articles in Usenet News.                             [21], non-standard




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Reference to previous message        Obsoletes:      RFC 1327, not for
being corrected and replaced.                        general usage.
Compare to "Supersedes:" below.
This field may in the future be
replaced with "Supersedes:".

Commonly used in Usenet News in      Supersedes:     son-of-RFC1036
similar ways to the "Obsoletes"                      [21], non-standard
header described above. In Usenet
News, however, Supersedes causes
a full deletion of the replaced
article in the server, while
"Supersedes" and "Obsoletes" in e-
mail is implemented in the client
and often does not remove the old
version of the text.

Only in Usenet News, similar to      Article-        son-of-RFC1036
"Supersedes:" but does not cause     Updates:        [21], non-standard
the referenced article to be
physically deleted.

Reference to specially important     Article-        son-of-RFC1036
articles for a particular Usenet     Names:          [21], non-standard
Newsgroup.

3.7 Other textual headers

Search keys for data base            Keywords:       RFC 822: 4.7.1
retrieval.                                           RFC 1036: 2.2.9.

Title, heading, subject. Often       Subject:        RFC 822: 4.7.1
used as thread indicator for                         RFC 1036: 2.1.4.
messages replying to or
commenting on other messages.

Comments on a message.               Comments:       RFC 822: 4.7.2.

Description of a particular body     Content-        RFC 1521: 6.2.
part of a message, for example a     Description:
caption for an image body part.

Organization to which the sender     Organization:   RFC 1036: 2.2.8,
of this article belongs.                             not standardized
                                                     for use in e-mail.

See Organization above.              Organisation:   Non-standard.








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Short text describing a longer       Summary:        RFC 1036: 2.2.10,
article. Warning: Some mail                          not standardized
systems will not display this                        for use in e-mail,
text to the recipient. Because of                    discouraged.
this, do not use this header for
text which you want to ensure
that the recipient gets.

A text string which identifies       Content-        RFC 1327, not for
the content of a message.            Identifier:     general usage.

3.8 Headers containing dates and
times

The time when a message was          Delivery-       RFC 1327, not for
delivered to its recipient.          Date:           general usage.

In Internet, the date when a         Date:           RFC 822: 5.1,
message was written, in X.400,                       RFC 1123: 5.2.14
the time a message was submitted.                    RFC 1036: 2.1.2.
Some Internet mail systems also
use the date when the message was
submitted.

A suggested expiration date. Can     Expires:        RFC 1036: 2.2.4,
be used both to limit the time of                    not standardized
an article which is not                              for use in e-mail.
meaningful after a certain date,
and to extend the storage of
important articles.

Time at which a message loses its    Expiry-Date:    RFC 1327, not for
validity. This field may in the                      general usage.
future be replaced by "Expires:".

Latest time at which a reply is      Reply-By:       RFC 1327, not for
requested (not demanded).                            general usage.

3.9 Quality information

Can be "normal", "urgent" or "non-   Priority:       RFC 1327, not for
urgent" and can influence                            general usage.
transmission speed and delivery.

Sometimes used as a priority         Precedence:     Non-standard,
value which can influence                            controversial,
transmission speed and delivery.                     discouraged.
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.


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A hint from the originator to the    Importance:     RFC 1327 and
recipients about how important a                     RFC 1911,
message is. Values: High, normal                     experimental
or low. Not used to control
transmission speed.

How sensitive it is to disclose      Sensitivity:    RFC 1327 and
this message to other people than                    RFC 1911,
the specified recipients. Values:                    experimental
Personal, private, company
confidential. The absence of this
header in messages gatewayed from
X.400 indicates that the message
is not sensitive.

Body parts are missing.              Incomplete-     RFC 1327, not for
                                     Copy:           general usage.

3.10 Language information

Can include a code for the           Language:       RFC 1327, not for
natural language used in a                           general usage.
message, e.g. "en" for English.

Can include a code for the           Content-        RFC 1766, proposed
natural language used in a           Language:       standard.
message, e.g. "en" for English.

3.11 Size information

Inserted by certain mailers to       Content-        Non-standard,
indicate the size in bytes of the    Length:         discouraged.
message text. This is part of a
format some mailers use when
showing a message to its users,
and this header should not be
used when sending a message
through the net. The use of this
header in transmission of a
message can cause several
robustness and interoperability
problems.

Size of the message.                 Lines:          RFC 1036: 2.2.12,
                                                     not standardized
                                                     for use in e-mail.

3.12 Conversion control

The body of this message may not     Conversion:     RFC 1327, not for
be converted from one character                      general usage.
set to another. Values:
Prohibited and allowed.


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Non-standard variant of              Content-        Non-standard.
Conversion: with the same values.    Conversion:

The body of this message may not     Conversion-     RFC 1327, not for
be converted from one character      With-Loss:      general usage.
set to another if information
will be lost. Values: Prohibited
and allowed.

3.13 Encoding information

Format of content (character set     Content-Type:   RFC 1049,
etc.) Note that the values for                       RFC 1123: 5.2.13,
this header are defined in                           RFC 1521: 4.
different ways in RFC 1049 and in                    RFC 1766: 4.1
MIME (RFC 1521), look for the
"MIME-version" header 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 1766 defines a parameter
"difference" to this header.

Information from the SGML entity     Content-SGML-   non-standard
declaration corresponding to the     Entity:
entity contained in the body of
the body part.

Coding method used in a MIME         Content-        RFC 1521: 5.
message body.                        Transfer-
                                     Encoding:

Only used with the value             Message-Type:   RFC 1327, not for
"Delivery Report" to indicates                       general usage.
that this is a delivery report
gatewayed from X.400.

Used in several different ways by    Encoding:       RFC 1154,
different mail systems. Some use                     RFC 1505,
it for a kind of content-type                        experimental.
information, some for encoding
and length information, some for
a kind of boundary information,
some in other ways.








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3.14 Resent-headers

When manually forwarding a           Resent-Reply-   RFC 822: C.3.3.
message, headers referring to the    To:,
forwarding, not to the original      Resent-From:,
message.  Note: MIME specifies       Resent-
another way of resending             Sender:,
messages, using the "Message"        Resent-From:,
Content-Type.                        Resent-Date:,
                                     Resent-To:,
                                     Resent-cc:,
                                     Resent-bcc:,
                                     Resent-
                                     Message-ID:

3.15 Security and reliability

Checksum of content to ensure        Content-MD5:    RFC 1864, proposed
that it has not been modified.                       standard.

Used in Usenet News to store         Xref:           RFC 1036: 2.2.13,
information to avoid showing a                       only in Usenet
reader the same article twice if                     News, not in e-
it was sent to more than one                         mail.
newsgroup. Only for local usage
within one Usenet News server,
should not be sent between
servers.

3.16 Miscellaneous

Name of file in which a copy of      Fcc:            Non-standard.
this message is stored.

Has been automatically forwarded.    Auto-           RFC 1327, not for
                                     Forwarded:      general usage.

Can be used in Internet mail to      Discarded-      RFC 1327, not for
indicate X.400 IPM extensions        X400-IPMS-      general usage.
which could not be mapped to         Extensions:
Internet mail format.

Can be used in Internet mail to      Discarded-      RFC 1327, not for
indicate X.400 MTS extensions        X400-MTS-       general usage.
which could not be mapped to         Extensions:
Internet mail format.

This field is used by some mail      Status:         Non-standard,
delivery systems to indicate the                     should never
status of delivery for this                          appear in mail in
message when stored. Common                          transit.
values of this field are:



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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.

Combinations of these characters
can occur, such as "Status: OR"
to indicate that a message is
downloaded but not deleted.



                          4. Acknowledgments

Harald Tveit Alvestrand, Ned Freed, Olle Järnefors, Keith Moore, Nick
Smith and several other people have helped me with compiling this list.
I especially thank Ned Freed and Olle Järnefors for their thorough
review and many helpful suggestions for improvements. I alone take
responsibility for any errors which may still be in the list.

An earlier version of this list has been published as part of [13].



                            5. References

Ref.    Author, title                                    IETF status
                                                         (July 1996)
-----   ---------------------------------------------    -----------
[1]     J. Postel: "Simple Mail Transfer Protocol",      Standard,
        STD 10, RFC 821, August 1982.                    Recommended

[2]     D. Crocker: "Standard for the format of ARPA     Standard,
        Internet text messages." STD 11, RFC 822,        Recommended
        August 1982.









Palme                                                        [Page 16]


draft-ietf-mailtext-mail-attributes-06.txt              October 1996

[3]     M.R. Horton, R. Adams: "Standard for             Not an offi-
        interchange of USENET messages", RFC 1036,       cial IETF
        December 1987.                                   standard,
                                                         but in
                                                         reality a de-
                                                         facto
                                                         standard for
                                                         Usenet News

[4]     M. Sirbu: "A Content-Type header header for      Standard,
        internet messages", RFC 1049, March 1988.        Recommended,
                                                         but can in
                                                         the future
                                                         be expected
                                                         to be
                                                         replaced by
                                                         MIME

[5]     R. Braden (editor): "Requirements for            Standard,
        Internet Hosts -- Application and Support",      Required
        STD-3, RFC 1123, October 1989.

[6]     D. Robinson, R. Ullman: "Encoding Header         Non-standard
        Header for Internet Messages", RFC 1154,
        April 1990.

[7]     S. Hardcastle-Kille: "Mapping between            Proposed
        X.400(1988) / ISO 10021 and RFC 822",  RFC       standard,
        1327 May 1992.                                   elective

[8]     H. Alvestrand & J. Romaguera: "Rules for         Proposed
        Downgrading Messages from X.400/88 to            standard,
        X.400/84 When MIME Content-Types are Present     elective
        in the Messages", RFC 1496, August 1993.

[9]     A. Costanzo: "Encoding Header Header for         Non-standard
        Internet Messages", RFC 1154, April 1990.

[10]    A. Costanzo, D. Robinson: "Encoding Header       Experimental
        Header for Internet Messages", RFC 1505,
        August 1993.

[11]    N. Borenstein & N. Freed: "MIME (Multipurpose    Draft
        Internet Mail Extensions) Part One:              Standard,
        Mechanisms for Specifying and Describing the     elective
        Format of Internet Message Bodies", RFC 1521,
        Sept 1993.

[12]    H. Alvestrand: "Tags for the Identification      Proposed
        of Languages", RFC 1766, February 1995.          standard,
                                                         elective




Palme                                                        [Page 17]


draft-ietf-mailtext-mail-attributes-06.txt              October 1996

[13]    J. Palme: "Electronic Mail", Artech House        Non-standard
        publishers, London-Boston January 1995.

[14]    R. Troost, S. Dorner: "Communicating             Experimental
        Presentation Information in Internet
        Messages: The Content-Disposition Header",
        RFC 1806, June 1995.

[15]    B. Kantor, P. Lapsley, "Network News Transfer    Proposed
        Protocol: "A Proposed Standard for the Stream-   standard
        Based Transmission of News", RFC 977, January
        1986.
[16]    1848  PS   S. Crocker, N. Freed, J. Galvin,      Proposed
        S. Murphy, "MIME Object Security Services",      standard
        RFC 1848, March 1995.

[17]    J. Myers, M. Rose: The Content-MD5 Header        Draft
        Header, RFC 1864, October 1995.                  standard

[18]    M. Horton, UUCP mail interchange format          Not an offi-
        standard, RFC 976, Januari 1986.                 cial IETF
                                                         standard,
                                                         but in
                                                         reality a de-
                                                         facto
                                                         standard for
                                                         Usenet News

[19]    T. Berners-Lee, R. Headering, H. Frystyk:        IETF draft
        Hypertext Transfer Protocol -- HTTP/1.0,
        draft-ietf-http-v10-spec-04.txt.

[20]    G. Vaudreuil: Voice Profile for Internet         Experimental
        Mail, RFC 1911, February 1996.

[21]    H. Spencer: News Article Format and              Not even an
        Transmission, June 1994,                         RFC, but
        FTP://zoo.toronto.edu/pub/news.ps.Z              still widely
        FTP://zoo.toronto.edu/pub/news.txt.Z             used and
                                                         partly
        This document is often referenced under the      almost a de-
        name "son-of-RFC1036".                           facto
                                                         standard for
                                                         Usenet News



                          6. Author's address

Jacob Palme                          Phone: +46-8-16 16 67
Stockholm University/KTH             Fax: +46-8-783 08 29
Electrum 230                         E-mail: jpalme@dsv.su.se
S-164 40 Kista, Sweden


Palme                                                        [Page 18]


draft-ietf-mailtext-mail-attributes-06.txt              October 1996


                             Appendix A:
Headers sorted by Internet RFC document in which they appear.


RFC 822
-------

bcc
cc
Comments
Date
From
In-Reply-To
Keywords
Message-ID
Received
References
Reply-To
Resent-
Resent-bcc
Resent-cc
Resent-Date
Resent-From
Resent-From
Resent-Message-ID
Resent-Reply-To
Resent-To
Return-Path
Sender
Sender
Subject
To

RFC 976
-------

"From " (followed by space, not colon (:")

RFC 1036
--------

Approved
Control
Distribution
Expires
Followup-To
Lines
Newsgroups
Organization
Path
Summary
Xref


Palme                                                        [Page 19]


draft-ietf-mailtext-mail-attributes-06.txt              October 1996

RFC 1049
--------

Content-Type

RFC 1327
--------

Alternate-recipient
Auto-Forwarded
Autoforwarded
Content-Identifier
Content-Return
Conversion
Conversion-With-Loss
Delivery-Date
Discarded-X400-IPMS-Extensions
Discarded-X400-MTS-Extensions
Disclose-Recipients
DL-Expansion-History
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 1505
--------

Encoding

RFC 1521
--------

Content-Description
Content-ID
Content-Transfer-Encoding
Content-Type
MIME-Version

RFC 1806
--------

Content-Disposition



Palme                                                        [Page 20]


draft-ietf-mailtext-mail-attributes-06.txt              October 1996

RFC 1864
--------

Content-MD5

RFC 1911
--------

Importance
Sensitivity

son-of-RFC1036 [21]
-------------------

Also-Control
Article-Names
Article-Updates
See-Also
Supersedes

Not Internet standard
---------------------

Apparently-to
Content-Base
Content-Length
Content-Location
Content-SGML-Entity
Encoding
Errors-To
Return-Receipt-To
Fax
"From " (not followed by ":")
Telefax
Fcc
Mail-System-Version
Mailer
Organisation
Originating-Client
Phone
Status
Supersedes
X400-Content-Return
X-Mailer
X-Newsreader










Palme                                                        [Page 21]


draft-ietf-mailtext-mail-attributes-06.txt              October 1996

                             Appendix B:
                         Alphabetical index

Section Heading-header
------- --------------

3.3     Also-Control
3.6     See-Also
3.3     Alternate-Recipient
3.4     Apparently-To
3.4     Approved
3.6     Article-Names
3.6     Article-Updates
3.16    Auto-Forwarded
3.4     bcc
3.4     cc
        Client, see Originating-Client
3.7     Comments
3.6     Content-Base
3.12    Content-Conversion
3.7     Content-Description
3.3     Content-Disposition
3.6     Content-ID
3.7     Content-Identifier
3.10    Content-Language see also Language
3.11    Content-Length
3.6     Content-Location
3.15    Content-MD5
3.4     Content-Return
3.13    Content-SGML-Entity
3.13    Content-Transfer-Encoding
3.13    Content-Type
3.3     Control
3.12    Conversion
3.12    Conversion-With-Loss
3.8     Date
3.8     Delivery-Date
        Delivery-Report, see Generate-Delivery-Report, Prevent-
        Delivery-Report, Non-Delivery-Report, Content-Type
        Description, see Content-Description
3.16    Discarded-X400-IPMS-Extensions
3.16    Discarded-X400-MTS-Extensions
3.3     Disclose-Recipients
        Disposition, see Content-Disposition
3.4     Distribution
3.2     DL-Expansion-History-Indication
3.13    Encoding see also Content-Transfer-Encoding
3.4     Errors-To
3.8     Expires
        Extension see Discarded-X400-IPMS-Extensions, Discarded-
        X400-MTS-Extensions
3.4     Fax
3.16    Fcc
3.4     Followup-To

Palme                                                        [Page 22]


draft-ietf-mailtext-mail-attributes-06.txt              October 1996

        Forwarded, see Auto-Forwarded
3.4     From
3.4     Generate-Delivery-Report
        History, see DL-Expansion-History-Indication
        ID, see Content-ID and Message-ID
        Identifier, see Content-ID and Message-ID
3.9     Importance
3.6     In-Reply-To
3.9     Incomplete-Copy
3.7     Keywords
3.10    Language see also Content-Language
        Length see Content-Length
3.11    Lines
3.4     Mail-System-Version see also X-mailer
3.4     Mailer
        MD5 see Content-MD5
3.6     Message-ID
3.13    Message-Type
3.3     MIME-Version
3.4     Newsgroups
        Newsreader, see X-Newsreader
3.6     Obsoletes
3.7     Organisation
3.7     Organization
3.3     Original-Encoded-Information-Types
3.4     Originating-Client
3.2     Path
3.4     Phone
3.9     Precedence
3.4     Prevent-NonDelivery-Report
3.9     Priority
3.2     Received
        Recipient, see To, cc, bcc, Alternate-Recipient, Disclose-
        Recipient
3.6     References
3.8     Reply-By
3.4     Reply-To, see also In-Reply-To, References
3.14    Resent-
        Return see also Content-Return
3.2     Return-Path
3.5     Return-Receipt-To
3.4     Sender
3.9     Sensitivity
3.16    Status
3.7     Subject
3.7     Summary
3.6     Supersedes
3.4     Telefax
3.4     To
        Transfer-Encoding see Content-Transfer-Encoding
        Type see Content-Type, Message-Type, Original-Encoded-
        Information-Types
        Version, see MIME-Version, X-Mailer
3.4     X400-Content-Return

Palme                                                        [Page 23]


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3.4     X-Mailer see also Mail-System-Version
3.4     X-Newsreader
3.15    Xref




















































Palme                                                        [Page 24]


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