One document matched: draft-ietf-drums-MHRegistry-00.txt
Network Working Group Jacob Palme
Internet Draft Stockholm University/KTH, Sweden
draft-ietf-drums-MHRegistry-00.txt January 1997
Category: Informational Expires August 1997
Mail Header Registration Procedure
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
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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 RFCs.. Distribution of this memo is unlimited.
Abstract
Various IETF standards and e-mail software products use various
e-mail header fields. This memo specifies a procedure for the
registration of e-mail header field names, to reduce the risk that
two different mail products use the same header name in different
ways. A proposed initial content of the header name registry at
start-up is specifed in an appendix to this ietf-draft.
Table of contents
1. Introduction
2. Which Headers are Registered
3. Who can Register a Header Name
4. Registration Procedure
4.1 Present the Request for Registration to the
Community
4.2 Submit the Header name to the IANA for
Registration
5. Clarifications On Specific Issues
5.1 E-mail Requirements for a Limited Number of
Headers
5.2 Header Status
5.3 Requirements for a Published Specification
5.4 Identification of Security Considerations
5.5 Recommendations and Standards Status
6. Security Considerations
7. Acknowledgments
8. References
9. Author's address
10. Appendix: Proposed initial content of the IETF header
name registry
Temporary comment (not to be included in the published RFC)
The first version is based mainly on two previous documents:
RFC 1590: Media registration
draft-ietf-mailext-mail-attributes-07.txt
This version will need more discussion on at least the following
points:
- Should every header get its own OID? Would this make conversion
of Internet e-mail headers to X.400 eaier?
- How much explanation should the header registry contain for each
header?
- Which are the allowed values of the status field in the
registry?
Differences between draft-palme-MHRegistry-00.txt and this revised
version draft-ietf-drums-MHRegistry-00.txt:
Two non-standard headers have been added in the appendix,
"For-Comment" and "For-Handling". They are variants of "To:" which
indicate what action this recipient is asked to perform when
receiving this message.
1. Introduction
Many different Internet standards, other RFCs and e-mail software
products define headers which may occur on Internet mail messages
and/or Usenet News articles. There is an obvious risk that the
same header name is used in different ways by different software
products.
The solution proposed in RFC 822, to allow header names beginning
with "X-" for non-standard header names has several drawbacks. One
is that it does not preclude two different products using the same
"X-" header name with different semantic meaning. Another is that
if an "X-" header gets popular and much used, and is to become a
standard, there is a problem with removing the "X-" in front of an
already much used header.
Because of this, an IANA registry for e-mail and Usenet News
header field names is needed.
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 header name, colon, and followed by the field
value(s)
2. Which Headers are Registered
The header name registry can contain headers from the following
sources:
- Internet standards
- RFCs which are not Internet standards
- Non-Internet standards
- Other commonly used headers
- Sometimes used headers whose use is discouraged. The use of a
header
name may be discouraged because it is badly defined, ambigous or
used
in different ways by different software. The purpose of
registering
discouraged headers is to avoid their use in their present or
any
other future semantic meaning.
The registry is intended to contain headers used in messaging
(e-mail, Usenet News, etc.) but not HTTP-only headers.
3. Who can Register a Header Name
Header names from Internet standards are registered by IETF
together with the standard specifying the header.
Headers in other RFCs are registered when the RFCs are published.
Anyone can propose the registry of additional headers, but such
headers should be approved by the IETF application area managers
before accepted in the registry. The procedure described in this
memo is followed by the IANA for review and approval of new e-mail
headers. This is not a formal standards process, but rather an
administrative procedure intended to allow community comment and
sanity checking without excessive time delay.
4. Registration Procedure
4.1 Present the Request for Registration to the Community
Send a proposed header to the "mail-headers@segate.sunet.se"
mailing list. This mailing list has been established for the sole
purpose of reviewing proposed e-mail headers. You can subscribe to
the list by sending a message to listserv@segate.sunet.se
containing in the text a line with
"subscribe mail-headers " followed by our name (not your e-mail
address), and unsubscribe with a message "unsubscribe
mail-headers".
Archives of this list are available
by anonymous FTP from
ftp://segate.sunet.se/lists/mail-headers/
by HTTP from
http://segate.sunet.se/archives/mail-headers.html
by E-MAIL
send a message to
LISTSERV@SEGATE.SUNET.SE with the text "INDEX mail-headers"
to get a list of the archive files, and then a new message
"GET <file name>" to retrieve the archive files.
The FTP and E-MAIL archives are best if you want to retrieval
all messages during a month or more, while the HTTP archives
are better if you want to browse and find particular messages
to download.
The intent of the public posting is to solicit comments and
feedback on the choice of header name, the unambiguity of the
references with respect to versions and external profiling
information, the choice of which OIDs to use, and a review of the
security considerations section. It should be noted that the
proposed header name does not need to make sense for every
possible application. If the header name is intended for a limited
or specific use, this should be noted in the submission.
4.2 Submit the Header name to the IANA for Registration
After at least two weeks, submit the proposed header to the IANA
for registration. The request and supporting documentation should
be sent to "iana@isi.edu". Provided a reasonable review period has
elapsed, the IANA will register the header, assign an OID under
the IANA branch, and make the header registration available to the
community.
The header registrations will be posted in the anonymous FTP
directory "ftp.isi.edu:in-notes/mail-headers" and the header will
be listed in the periodically issued "Assigned Numbers" RFC [2].
The header description may be published as an Informational RFC by
sending it to "rfc-editor@isi.edu" (please follow the instructions
to RFC authors [3]).
5. Clarifications On Specific Issues
5.1 E-mail Requirements for a Limited Number of Headers
Issue: In the asynchronous mail environment, where information on
the capabilities of the remote mail agent is not available to the
sender, maximum interoperability is attained by restricting the
number of headers used to those "common" headers expected to be
widely implemented. This was asserted as a reason to limit the
number of possible headers and resulted in a registration process
with a significant hurdle and delay for those registering headers.
5.2 Header Status
Any header in the registry should be marked with a status, which
has one of the values specified below:
IETF standard. Specified in an IETF standard.
IETF draft standard. Specified in an IETF draft standard.
IETF proposed Specified in an IETF proposed standard.
standard.
IETF experimental Specified in an IETF experimental
standard. standard.
X.400. Used to mark headers which are defined
in RFC 1327 for use in messages from or
to Internet mail/X.400 gateways, and
which have not been standardized for
general usage in the exchange of
messages between Internet mail-based
systems.
Usenet News only, De facto standard in Usenet News, may
not in e-mail. occur in messages gatewayed from Usenet
News to e-mail, no defined meaning in
e-mail.
Non-standard, only Used in Usenet News, may occur in
in Usenet News, not messages gatewayed from Usenet News to
in e-mail. e-mail, no defined meaning in e-mail.
Usenet news only, De facto standard in Usenet News, may
discouraged in occur in messages gatewayed from Usenet
e-mail. News to e-mail, but such practice is
discouraged.
Not standardized for Used to mark headers defined only for
use in e-mail. 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.
Other standard. Defined in standard developed by another
standards making body than IETF.
Non-standard. This header is not specified in any of
the RFCs which define Internet
protocols, including Internet Standards,
Draft Standards, Proposed Standards and
Experimental 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 or
historical, 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.
5.3 Requirements for a Published Specification
Issue: Header registration requires an RFC specifying the header,
except for header names marked as discouraged in the header
registry.
The following information should be provided when applying for
registry of a new e-mail or Usenet News header:
- Header name.
- Status, one of the statuses specified in section 5.2 above.
- If the header is specified in an RFC, the number of this RFC.
- If the header is specified in another standard than an RFC, a
reference to this standard.
- If the header is not specified in an RFC, a textual description
should be enclosed, which describes the header, its intended use
and discusses security considerations.
5.4 Identification of Security Considerations
Issue: The registration process requires the identification of any
known security problems with the header name.
Comment: It is not required that the header be secure or that it
be free from risks, but that the known risks be identified.
Publication of a header name does not require an exhaustive
security review, and the security considerations section is
subject to continuing evaluation. Additional security
considerations should be periodically published in an RFC by IANA.
5.5 Recommendations and Standards Status
Issue: The registration of a header does not imply endorsement,
approval, or recommendation by IANA or IETF or even certification
that the specification is adequate.
6. Security Considerations
This memo does not address specific security issues but outlines a
security review process for headers
7. Acknowledgments
Harald Tveit Alvestrand, Ned Freed, Olle Järnefors, Keith Moore,
Nick Smith and several other people have helped me with compiling
the list in the appendix. I alone take responsibility for any
errors which may still be in the list.
8. References
Ref. Author, title IETF status
(July 1996)
---- ------------------------------------------ -------------
[1] J. Postel: "Simple Mail Transfer Standard,
Protocol", STD 10, RFC 821, August 1982. Recommended
2] D. Crocker: "Standard for the format of Standard,
ARPA Internet text messages." STD 11, RFC Recommended
822, August 1982.
[3] M.R. Horton, R. Adams: "Standard for Not an
interchange of USENET messages", RFC 1036, offi-cial IETF
December 1987. standard, but
in reality a
de-facto
standard for
Usenet News
4] M. Sirbu: "A Content-Type 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 Required
Support", STD-3, RFC 1123, October 1989.
[6] D. Robinson, R. Ullman: "Encoding Header Non-standard
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 elective
Present in the Messages", RFC 1496, August
1993.
[9] A. Costanzo: "Encoding Header for Internet Non-standard
Messages", RFC 1154, April 1990.
10] A. Costanzo, D. Robinson: "Encoding Header Experimental
for Internet Messages", RFC 1505, August
1993.
[11] N. Borenstein & N. Freed: "MIME Draft Standard,
(Multipurpose Internet Mail Extensions) elective
Part One: Mechanisms for Specifying and
Describing the Format of Internet Message
Bodies", RFC 1521, Sept 1993.
[12] H. Alvestrand: "Tags for the Proposed
Identification of Languages", RFC 1766, standard,
February 1995. elective
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 Proposed
Transfer Protocol: "A Proposed Standard standard
for the Stream-Based Transmission of
News", RFC 977, January 1986.
[16] 1848 PS S. Crocker, N. Freed, J. Proposed
Galvin, S. Murphy, "MIME Object Security standard
Services", RFC 1848, March 1995.
[17] J. Myers, M. Rose: The Content-MD5 Header, Draft standard
RFC 1864, October 1995.
[18] M. Horton, UUCP mail interchange format Not an
standard, RFC 976, Januari 1986. offi-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 still
FTP://zoo.toronto.edu/pub/news.ps.Z widely used and
FTP://zoo.toronto.edu/pub/news.txt.Z partly almost a
de-facto
This document is often referenced under standard for
the name "son-of-RFC1036". Usenet News
22] J. Palme: Common Internet Message Headers. Informational
draft-ietf-mailext-mail-attributes-07.txt.
January 1997.
9. 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
10. Appendix: Proposed initial content of the IETF header name
registry
Note: The descriptions in the leftmost columns are intentionally
very brief and may therefore not give a complete and fully
accurate description of the header.
Hint on usage Header name Source Status
-------------- ----------- ------------------ ----------------
Special Usenet Also-Contro son-of-RFC1036 Non-standard,
News actions. l: [21]. only in Usenet
News, not in
e-mail.
Controls X.400 Alternate-R RFC 1327. X.400.
forwarding. ecipient:
Inserted by Apparently- RFC 1211 and [22]. Non-standard,
Sendmail. To: discouraged.
Mark of Approved: RFC 1036: 2.2.11. Only in Usenet
approval by News, not in
moderator. e-mail.
Specially Article-Nam son-of-RFC1036 Non-standard.
important es: [21].
articles.
Revised Article-Upd son-of-RFC1036 Non-standard.
version ates: [21].
article.
Has been Auto-Forwar RFC 1327. X.400.
automatically ded:
forwarded.
Recipients not bcc: RFC 822: 4.5.3, IETF standard.
to be RFC 1123:
disclosed. 5.2.15-16, 5.3.7.
Secondary cc: RFC 822: 4.5.2, IETF standard.
recipients. RFC 1123.
5.2.15-16, 5.3.7.
Comments on a Comments: RFC 822: 4.7.2. IETF standard.
message.
Base for Content-Bas In forthcoming Soon IETF
resolving e: MHTML standard. proposed
relative URLs. standard.
Conversion Content-Con See [22]. Non-standard.
control. version:
Description of Content-Des RFC 1521: 6.2. IETF draft
body part. cription: standard.
Inline or Content-Dis RFC 1806. IETF
attachment. position: experimental
standard.
Unique ID of Content-ID: RFC 1521: 6.1. IETF draft
one body part. standard.
Text string Content-Ide RFC 1327. X.400.
identifier. ntifier:
Language(s) of Content-Lan RFC 1766. IETF proposed
body part. guage: standard.
Size in bytes. Content-Len See [22]. Non-standard,
gth: discouraged.
URI for body Content-Loc In forthcoming Soon IETF
part. ation: MHTML proposed proposed
standard. standard.
Checksum of Content-MD5 RFC 1864. IETF proposed
content. : standard.
Return content Content-Ret RFC 1327. X.400.
in X.400 urn:
delivery
notifications?
.
From the SGML Content-SGM Other standard.
entity L-Entity:
declaration.
Coding method. Content-Tra RFC 1521: 5. IETF draft
nsfer-Encod standard.
ing:
Format of Content-Typ RFC 1049, IETF draft
content. e: RFC 1123: 5.2.13, standard.
RFC 1521: 4.
RFC 1766: 4.1
Special Usenet Control: RFC 1036: 2.1.6. Only in Usenet
News actions News, not in
only. e-mail.
Body may not Conversion- RFC 1327. X.400.
be converted With-Loss:
with loss.
Body may not Conversion: RFC 1327. X.400.
be converted.
When message Date: RFC 822: 5.1, IETF standard.
was created. RFC 1123: 5.2.14
RFC 1036: 2.1.2.
When message Delivery-Da RFC 1327. X.400.
was delivered. te:
X.400 Discarded-X RFC 1327. X.400.
extensions not 400-IPMS-Ex
mapped. tensions:
X.400 Discarded-X RFC 1327. X.400.
extensions not 400-MTS-Ext
mapped. ensions:
Tell recipient Disclose-Re RFC 1327. X.400.
about other cipients:
recipients.
Limitation of Distributio RFC 1036: 2.2.7. Usenet news
distribution n: only, not in
area. e-mail.
Trace of lists DL-Expansio RFC 1327. X.400.
passed. n-History-I
ndication:
Several Encoding: RFC 1154, IETF
different RFC 1505, experimental
incompatible standard.
uses.
Where to send Errors-To: See [22]. Non-standard,
notifications. discouraged.
Expiration Expires: RFC 1036: 2.2.4. Usenet news
date. only, not in
e-mail.
Expiration Expiry-Date RFC 1327. X.400.
date. :
Fax number of Fax: Non-standard.
the
originator.
File where Fcc: See [22]. Non-standard.
message is
stored.
Where to Followup-To RFC 1036: 2.2.3. Usenet news
discuss item : only, not in
further. e-mail.
Variant of For-Comment See [22]. Non-standard.
"To:" :
Variant of For-Handlin See [22]. Non-standard.
"To: g:
(1) Message From See [22]. Discouraged in
separator in transport of
files. e-mail.
(2) Usenet From RFC 976: 2.4 Usenet news
news delivery or only, not in
path. >From e-mail.
Author From: RFC 822: 4.4.1, IETF standard.
RFC 1123:
5.2.15-16, 5.3.7,
RFC 1036 2.1.1
Delivery Generate-De RFC 1327. X.400.
report livery-Repo
generation rt:
control.
Values: High, Importance: RFC 1327 and IETF
normal or low. RFC 1911. experimental
standard.
Message being In-Reply-To RFC 822: 4.6.2.
replied to. :
Body parts are Incomplete- RFC 1327. X.400.
missing. Copy:
Search keys Keywords: RFC 822: 4.7.1
for retrieval. RFC 1036: 2.2.9.
Language of Language: RFC 1327, X.400.
message.
Size of the Lines: RFC 1036: 2.2.12. Usenet news
message. only, not in
e-mail.
Generating Mail-System Non-standard,
client -Version: discouraged.
software.
Generating Mailer: Non-standard,
client discouraged.
software.
Unique ID of Message-ID: RFC 822: 4.6.1 IETF standard.
this message. RFC 1036: 2.1.5.
Report or Message-Typ RFC 1327. X.400.
message. e:
Version of MIME-Versio RFC 1521: 3. IETF draft
MIME. n: standard.
Newsgroups Newsgroups: RFC 1036: 2.1.3, Usenet news
getting this see also[22]. only,
article. discouraged in
e-mail.
Previous Obsoletes: RFC 1327. X.400.
message being
replaced.
Sender Organisatio Discouraged.
organzation. n:
Sender Organizatio RFC 1036: 2.2.8. Usenet news
organization. n: only,
discouraged in
e-mail.
Body part Original-En RFC 1327. X.400.
types in coded-Infor
message. mation-Type
s:
Generating Originating Non-standard,
client -Client: discouraged.
software.
List of MTAs Path: RFC 1036: 2.2.6. Usenet news
passed. only, not in
e-mail.
Phone number Phone: . Non-standard
of the
originator.
Priority, Precedence: See [22]. Non-standard,
might controversial,
influence discouraged.
speed.
Non-delivery Prevent-Non RFC 1327. X.400.
report Delivery-Re
control. port:
Priority, Priority: RFC 1327. X.400.
might
influence
speed.
Trace of MTAs Received: RFC 822: 4.3.2, IETF standard.
passed. RFC 1123: 5.2.8.
Reference to References: RFC 822: 4.6.3 IETF standard.
other RFC 1036: 2.1.5.
messages.
Latest reply Reply-By: RFC 1327. X.400.
time.
Where to send Reply-To: RFC 822: 4.4.3, IETF standard
replies. RFC 1036: 2.2.1 but
see also [22]. controversial.
Information Resent-Repl RFC 822: C.3.3. IETF standard.
about manual y-To:,
forwarding. Resent-From:,
Resent-Sender:,
Resent-From;,
Resent-Date;,
Resent-To:,
Resent-cc:,
Resent-bcc:,
Resent-Mess
age-ID:
Envelope info Return-Path RFC 821, IETF standard.
at final : RFC 1123: 5.2.13.
delivery.
Where to send Return-Rece See [22]. Non-standard,
notifications. ipt-To: discouraged.
Related See-Also: Son-of-RFC1036 Non-standard.
articles. [21].
Sender if not Sender: RFC 822: 4.4.2, IETF standard.
same as in RFC 1123:
from header. 5.2.15-16, 5.3.7.
Disclosure Sensitivity RFC 1327 and IETF
secrecy. : RFC 1911. experimental
standard.
Whether Status: See [22]. Non-standard,
message has should never
been appear in mail
delivered. in transit.
Title, Subject: RFC 822: 4.7.1 IETF standard.
heading, RFC 1036: 2.1.4.
subject.
Short version Summary: RFC 1036: 2.2.10. Usenet news
of long only,
message. discouraged.
Replaces Supersedes: Son-of-RFC1036 Non-standard.
previous [21].
article.
Fax number of Telefax: Non-standard.
the
originator.
Primary To: RFC 822: 4.5.1, IETF standard.
recipients. RFC 1123:
5.2.15-16, 5.3.7.
Generating X-Mailer: Non-standard.
client
software.
Generating X-Newsreade Non-standard.
client r
software.
Control of X400-Conten Non-standard.
content-return t-Return:
.
Other Xref: RFC 1036: 2.2.13. Usenet news
newsgroups only, not in
getting the e-mail.
same article.
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