draft-ietf-mailext-mail-attributes-03.txt  -->   draft-ietf-mailext-mail-attributes-04.txt

view Side-By-Side changes





                  Common Internet Message Attributes 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 RFC-s.. RFCs.. Distribution of this memo is unlimited.



                            Abstract

This memo contains a table of commonly occurring attributes headers in headings and on envelopes of
e-mail messages. The document compiles information from other RFC-s RFCs such
as RFC 821, RFC 822, RFC 1036, RFC 1123, RFC 1327, RFC 1496, RFC 1521, RFC 1766 1766,
RFC 1806 and RFC 1806. 1864. A few commonly occurring attributes headers which are not
defined in RFC-s RFCs are also included. For each attribute, header, the memo gives a
short description and a reference to the RFC, RFC in which the attribute header is
defined. The postscript version of this memo shows the changes
as compared to version 02.







Palme                                                           [Page 1]
draft-ietf-mailext-mail-attributes-03.txt                 November 1995
draft-ietf-mailext-mail-attributes-04.txt                      May 1996


                         Table of contents

1. Introduction

2. Use of gatewaying attributes headers

3. Table of attributes headers

   3.1 Phrases used in the tables
   3.2  Addressing Trace information
   3.3  Envelope Format and format control information
   3.4 Sender and recipient indication
   3.5 Response control
   3.6 Message identification and referral attributes headers
   3.7 Other textual attributes headers
   3.8  Attributes 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-attributes Resent-headers
   3.15 Security and reliability
   3.16 Miscellaneous

4. Acknowledgments

5. References

6. Author's address

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

Appendix B: Alphabetical index


















Palme                                                           [Page 2]
draft-ietf-mailext-mail-attributes-03.txt                 November 1995
draft-ietf-mailext-mail-attributes-04.txt                      May 1996


                         1. Introduction

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

The document contains all heading attributes headers which the author has
found in the following Internet standards: RFC 821 [1], , RFC 822 [2],
RFC 1036 [3], RFC 1123 [5], RFC 1327 [7], RFC 1496 [8], RFC 1521 [11],
RFC 1766 [12] and [12], RFC 1806 [14]. [14] and RFC 1864[17]. 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 1421-1424, "Privacy Enhancement for Internet
Electronic Mail", 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
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 attributes headers which often can be found in e-mail headings but are
not part of any Internet standard are also included.

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

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 by anonymous FTP 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.




Palme                                                           [Page 3]
draft-ietf-mailext-mail-attributes-04.txt                      May 1996

                 2. Use of gatewaying attributes headers

RFC 1327 defines a number of new attributes headers in Internet mail, which
are defined to map attributes headers which X.400 has but which were
previously not standardized in Internet mail. The fact that an
attribute 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 attribute header is recommended for messages wholly
within Internet mail. Some of these attributes headers may eventually get
accepted also for usage within see
widespread implementation and use in Internet mail, but they are, when at the time of
this is written (July 1995) writing (May 1996) they are not recommended for such usage.

Fields widely implemented or used.

Headers defined 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 fields headers are however not standardized for use in Internet e-mail
and should be handled with caution.

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 caution by e-mail headers sometimes with
English, sometimes with American spelling.










Palme                                                          [Page 3]
draft-ietf-mailext-mail-attributes-03.txt                 November 1995 agents.




                      3. Table of attributes headers

3.1 Phrases used in the tables


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

"not standardized       Used to mark attributes headers defined only in RFC 1036
for use in e-mail"      1036      for use in Usenet News. These attributes headers have no
                        standard meaning when appearing in e-
                        mail, 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 standard for Usenet News, is not an accepted
                        IETF standard or on the IETF standards track.

"non-standard"          This attribute header is not specified in any of
                        those
                        referenced RFC-s RFCs which are define Internet
                        standards,
                        protocols, including Internet Standards, draft
                        standards or proposed standards. The attribute header
                        appears here because it is common often appears in e-mail e-
                        mail or Usenet News headers. News. Usage of these attributes headers is
                        not in general recommended.



Palme                                                           [Page 4]
draft-ietf-mailext-mail-attributes-04.txt                      May 1996

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

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

"for limited use"       Attributes defined in a so-called
                        "experimental" Internet standard. These should
                        be used only if both parties agree.

"experimental"          This attribute header is used for newly defined
                        attributes, headers,
                        which are to be tried out before entering the
                        IETF standards track.

Palme                                                          [Page 4]
draft-ietf-mailext-mail-attributes-03.txt                 November 1995 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 Addressing Trace information

Original sender. Should in           MAIL FROM       RFC 821,
Internet be empty ("MAIL FROM:                       RFC 1123: 5.2.9.
<>") when sending notifications,
and be the list administrator
when forwarding from a
distribution list. This value may
for gatewayed messages contain a
chain of hosts to be passed in
sequence to reach the original
sender (i.e. a relative address).
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.

Recipient to which message is to     RCPT TO         RFC 821,
be delivered. Relative address                       RFC 1123: 5.2.6.
was allowed in RFC 821, but later
prohibited in RFC 1123.

3.3 Envelope and format
information

All that is inside the envelope.     DATA            RFC 821,
                                                     RFC 1123: 5.2.8.

Trace of MTA-s MTAs which a message has    Received:       RFC 822: 4.3.2,
has
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.

List of MTA-s passed.                Path:           RFC 1036: 2.2.6,
                                                     not standardized
                                                     for use in e-mail.



Palme                                                           [Page 5]
draft-ietf-mailext-mail-attributes-04.txt                      May 1996

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

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



Palme                                                          [Page 5]
draft-ietf-mailext-mail-attributes-03.txt                 November 1995 in e-
                                                     mail.

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

Special informational message.       Message-Type:   RFC 1327, not for
                                     Delivery        general usage.
                                     Report

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, such 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: cc: and Bcc:
heading fields.
bcc: headers.

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

3.4 Sender and recipient
indication

Author, approver

Authors or persons taking            From:           RFC 822: 4.4.1,
responsibility for the message.                      RFC 1123: 5.2.15-
                                                     16, 5.3.7.

Moderator 5.3.7,
                                                     RFC 1036 2.1.1

Name of the moderator of the         Approved:       RFC 1036: 2.2.11,
newsgroup to which this message                      not standardized
is sent; necessary on an article                     for use in e-mail.

Sender information inside
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.



Palme                                                           [Page 6]
draft-ietf-mailext-mail-attributes-04.txt                      May 1996

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

Main
header.

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

Additional recipients.               Cc:

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


Palme                                                          [Page 6]
draft-ietf-mailext-mail-attributes-03.txt                 November 1995

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

In Usenet News: group group(s) to which    Newsgroups:     RFC 1036: 2.1.3,
this article was posted.                             not standardized
Some systems provide this field header                     and controversial
also in e-mail although it is not                    for use in e-mail.
standardized there.
Unfortunately, the field header can
appear in e-mail with two
different and contradictory
meanings:
(a) Indicates the newsgroup
recipient of a message sent to
both e-mail and Usenet News
recipients.
(b) In a personally addressed
reply to a message in a news-
group, indicate 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, MTA-s 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.

Limitation on where this message

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




Palme                                                           [Page 7]
draft-ietf-mailext-mail-attributes-04.txt                      May 1996

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:





Palme                                                          [Page 7]
draft-ietf-mailext-mail-attributes-03.txt                 November 1995
                                     Client:, X-
                                     Mailer, X-
                                     Newsreader

3.5 Response control

This heading field header is meant to indicate     Reply-To:       RFC 822: 4.4.3,
indicate
where the sender wants                      controversial. 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).

There has been various
suggestions to differentiate
between these two uses of "Reply-
To", with new

Some mail systems use this header fields names
"Personal-Reply-To", "Group-Reply-
To" or "Wide-Reply-To". None of
these proposals have been
accepted.

In practice, "Reply-To" is often
used
to indicate a neater format
for better form of the
e-mail address of the
sender than that given in the
"From" field. In this case, it
would be better to put the neater
format directly in the "From"
field.

A well-known sender.
Some mailing list
software will optionally insert
"Reply-To" with expanders puts
the name of the list into messages distributed by
the list. in this
header. These practices are
controversial. The personal
opinion of the author of this RFC
is that you this header should avoid
using "Reply-To" until IETF has
defined less ambiguous
constructs. This opinion be
avoided except in special cases,
but this is
however also controversial and a personal opinion
not shared by everyone.







Palme                                                          [Page 8]
draft-ietf-mailext-mail-attributes-03.txt                 November 1995 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.

Palme                                                           [Page 8]
draft-ietf-mailext-mail-attributes-04.txt                      May 1996

In e-mail, this heading field header is used in
a message which is sent to both e-mail e-
mail and Usenet News, to show
where follow-up in Usenet news is
wanted. The field 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.

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, and a new standard
for delivery notifications
specifies how requests for
notifications are specified by a
new parameter "NOTIFY" to the
"RCPT TO" SMTP command.

An IETF group is working on a        Disposition-    Do not use until
standard for receipt notifica-       Notification-   the proposal from
tions (note that this is not the     To:             this IETF group is
same as delivery notifications).                     ready and accepted
This group is discussing this new                    by IETF.
heading field, but no agreement
has been reached yet. 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     Return:         general usage.
non-delivery notifications.

Palme                                                          [Page 9]
draft-ietf-mailext-mail-attributes-03.txt                 November 1995


Indicates whether the content of     RET in DRPT     In forthcoming new
a message is to be returned with     SMTP exten-     Internet standard.
non-delivery notifications.          sion

3.6 Message identification and
referral attributes headers

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

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

Reference to other related           References:     RFC 822: 4.6.3. 4.6.3
messages.                                            RFC 1036: 2.1.5.

Reference to previous message        Obsoletes:      RFC 1327, not for
being corrected and replaced.                        general usage.

Used
Compare to "Supersedes:" below.


Palme                                                           [Page 9]
draft-ietf-mailext-mail-attributes-04.txt                      May 1996

Commonly used in Usenet News in      Supersedes:     Non-standard.
similar ways to the "Obsoletes"
header described above. In Usenet
News, however, Supersedes causes
a full deletion of the replaced
message in Usenet News the server, while
Obsoletes is implemented in similar       Supersedes:     Non-standard.
ways to the "Obsoletes" attribute
described above.
client and often does not remove
the old version of the text.

3.7 Other textual attributes headers

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

Title, heading, subject. Often       Subject:        RFC 822: 4.7.1. 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.                   description:                   Description:

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

See Organization above.              Organisation:   Non-standard.

Short text describing a longer       Summary:        RFC 1036: 2.2.10,
message. 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 field 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:            Identifier:     general usage.

Palme                                                          [Page 10]
draft-ietf-mailext-mail-attributes-03.txt                 November 1995

3.8 Attributes 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. 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.

Palme                                                          [Page 10]
draft-ietf-mailext-mail-attributes-04.txt                      May 1996

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.                                            general usage.

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.

Can be high, normal or low and is

A hint from the originator to the    Importance:     RFC 1327, not for
only used in the recipient client
recipients about how important a                     general usage.
(UA).

Can be personal, private, company
message is. Values: High, normal
or low. Not used to control
transmission speed.

How sensitive it is to disclose      Sensitivity:    RFC 1327, not for
confidential or absent.
this message to other people than                    general usage.
the specified recipients. Values:
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.






Palme                                                          [Page 11]
draft-ietf-mailext-mail-attributes-03.txt                 November 1995

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.



Palme                                                          [Page 11]
draft-ietf-mailext-mail-attributes-04.txt                      May 1996

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:    Length:         discouraged.
message text. Can 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 and is not recommended.
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.

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 field header are defined in                           RFC 1521: 4.
different ways in RFC 1049 and in
MIME (RFC 1521), look for the
"MIME-version" heading field 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.



Palme                                                          [Page 12]
draft-ietf-mailext-mail-attributes-04.txt                      May 1996

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




Palme                                                          [Page 12]
draft-ietf-mailext-mail-attributes-03.txt                 November 1995


Coding method
                                     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 content. 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 limited use.
a kind of boundary information,
some in other ways.

3.14 Resent-attributes Resent-headers

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

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 which        X400-IPMS-      general usage.
which could not be mapped to Internet         Extensions:
Internet mail format.

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

Palme                                                          [Page 13]
draft-ietf-mailext-mail-attributes-04.txt                      May 1996


                          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].







Palme                                                          [Page 13]
draft-ietf-mailext-mail-attributes-03.txt                 November 1995



                            5. References

Ref.    Author, title                                    IETF status
                                                         (July 1995)
                                                         (May 1996)
-----   ---------------------------------------------    -----------
-       -
[1]     J. Postel: "Simple Mail Transfer Protocol",      Standard,
        STD 10, RFC 821, August 1982.                    Recommended.                    Recommended

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

[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. News

[4]     M. Sirbu: "A Content-Type header field header for      Standard,
        internet messages", RFC 1049, March 1988.        Recommended.        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.      Required
        STD-3, RFC 1123, October 1989.

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





Palme                                                          [Page 14]
draft-ietf-mailext-mail-attributes-04.txt                      May 1996

[7]     S. Hardcastle-Kille: "Mapping between            Proposed
        X.400(1988) / ISO 10021 and RFC 822",  RFC       standard,
        1327 May 1992.                                   elective.                                   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.     elective
        in the Messages", RFC 1496, August 1993.

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

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





Palme                                                          [Page 14]
draft-ietf-mailext-mail-attributes-03.txt                 November 1995

[11]    N. Borenstein & N. Freed: "MIME (Multipurpose    Draft
        Internet Mail Extensions) Part One:              Standard,
        Mechanisms for Specifying and Describing the     elective.     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.
                                                         elective

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

[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


Palme                                                          [Page 15]
draft-ietf-mailext-mail-attributes-04.txt                      May 1996

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



                          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 15]
draft-ietf-mailext-mail-attributes-03.txt                 November 1995




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


RFC 821
-------

DATA
MAIL FROM
RCPT TO

RFC 822
-------

Bcc
Cc

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-ToResent-cc
Resent-To
Return-Path
Sender
Sender
Subject
To







Palme                                                          [Page 16]
draft-ietf-mailext-mail-attributes-04.txt                      May 1996

RFC 1036
--------

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

Palme                                                          [Page 16]
draft-ietf-mailext-mail-attributes-03.txt                 November 1995

RFC 1049
--------

Content-Type

RFC 1327
--------

Alternate-recipient
Auto-Forwarded
Autoforwarded
Content-identifier
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


Palme                                                          [Page 17]
draft-ietf-mailext-mail-attributes-04.txt                      May 1996

RFC 1521
--------

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

RFC 1806
--------

Content-Disposition


Palme                                                          [Page 17]
draft-ietf-mailext-mail-attributes-03.txt                 November 1995

RFC 1864
--------

Content-MD5

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

Apparently-to
Content-length
Encoding
Errors-To
Return-Receipt-To
Fax
Telefax
Fcc
Mail-System-Version
Mailer
Organisation
Originating-Client
Phone
Supersedes
X-Mailer
X-Newsreader


















Palme                                                          [Page 18]
draft-ietf-mailext-mail-attributes-03.txt                 November 1995
draft-ietf-mailext-mail-attributes-04.txt                      May 1996

                             Appendix B:
                         Alphabetical index

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

3.3     Alternate-Recipient
3.4     Apparently-To
3.4     Approved
3.16    Auto-Forwarded
3.4     Bcc     bcc
3.4     Cc     cc
        Client, see Originating-Client
3.7     Comments
3.12    Content-Conversion
3.7     Content-Description
3.3     Content-Disposition
3.6     Content-ID
3.7     Content-identifier     Content-Identifier
3.10    Content-Language see also Language
3.11    Content-Length
3.5
3.15    Content-MD5
3.4     Content-Return
3.13    Content-Transfer-Encoding
3.13    Content-Type
3.3     Control
3.12    Conversion
3.12    Conversion-With-Loss
3.3     DATA
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
3.5     Disposition-Notification-To
        Disposition, see Content-Disposition
3.4     Distribution
3.3
3.2     DL-Expansion-History-Indication
3.13    Encoding
3.5 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
3.15
3.16    Fcc
3.5
3.4     Followup-To
        Forwarded, see Auto-Forwarded
3.4     From
3.5
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


Palme                                                          [Page 19]
draft-ietf-mailext-mail-attributes-04.txt                      May 1996

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
3.2     MAIL FROM
3.4     Mail-System-Version see also X-mailer
3.4     Mailer
        MD5 see Content-MD5
3.6     Message-ID
3.3
3.13    Message-Type

Palme                                                          [Page 19]
draft-ietf-mailext-mail-attributes-03.txt                 November 1995
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     Original-Encoded-Information-Types
3.4     Originating-Client
3.3
3.2     Path
3.4     Phone
3.9     Precedence
3.5
3.4     Prevent-NonDelivery-Report
3.9     Priority
3.2     RCPT TO
3.3     Received
        Recipient, see To, cc, bcc, Alternate-Recipient, Disclose-
        Recipient
3.6     References
3.8     Reply-By
3.5     Reply-To
3.4     Reply-To, see also In-Reply-To, References
3.14    Resent-
3.5     RET in DRPT SMTP extension
        Return see also Content-Return
3.2     Return-Path
3.5     Return-Receipt-To
3.4     Sender
3.9     Sensitivity
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     X-Mailer see also Mail-System-Version
3.4     X-Newsreader






Palme                                                          [Page 20]

----