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draft-ietf-x400ops-postmaster-00.txt
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INTERNET DRAFT Nov 1992
Postmaster Convention for X.400 Operations
Sat Nov 14 21:58:15 CST 1992
C. Allan Cargille
University of Wisconsin
Allan.Cargille@cs.wisc.edu
This draft document is being circulated for comment.
If consensus is reached it may be submitted to the RFC
editor as a Proposed Standard protocol specification, for
use in X.400 in the Internet.
Please send comments to the author, or to the IETF OSI X.400
Operations Working Group mailing list
<ietf-osi-x400ops@cs.wisc.edu>.
The following text is required by the Internet-draft rules:
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. Internet Drafts may be
updated, replaced, or obsoleted by other documents
at any time. It is not appropriate to use Internet
Drafts as reference material or to cite them other
than as a "working draft" or "work in progress."
Please check the I-D abstract listing contained in
each Internet Draft directory to learn the current
status of this or any other Internet Draft.
Abstract:
Both RFC822 and 1173 (Host Requirements) require that
the email address "postmaster" be supported at all
hosts. This paper extends this concept to X.400 mail
domains which have registered RFC1327 mapping rules
(and therefore which appear to have normal RFC822-style
addresses).
Cargille Expires May 18, 1993 [Page 1]
DRAFT X.400 Postmaster Convention Nov 1992
1. Postmaster Convention in RFC822
Operating a reliable, large-scale electronic mail (email)
network requires cooperation between many mail managers and
system administrators. As noted in RFC822 [1], often mail
or system managers need to be able to contact a responsible
person at a remote host without knowing any specific user
name or address at that host. For that reason, both RFC822
and the Internet Host Requirements [2] require that the
address "postmaster" be supported at every Internet host.
2. Postmaster Convention and X.400
However, RFC822 is not the only email protocol being used in
the Internet. Some Internet sites are also running the
X.400 (1984) email protocol [3]. In the near future, the
1988 X.400 protocol is also expected to be in use [4].
RFC1327 specifies how to map between X.400 and RFC822
addresses [5]. When mapping rules are used, addresses map
cleanly between X.400 and RFC822. In fact, it is impossible
to determine by inspecting the address whether the recipient
is an RFC822 mail user or an X.400 mail user.
A paper by Rob Hagens and Alf Hansen describes an X.400
community known as the "Global Open MHS Community" (GO-MHS)
[6]. Many mail domains in the GO-MHS Community have
registered RFC1327 mapping rules. Therefore, users in those
domains have RFC822-style email addresses, and these email
domains are a logical extension of the RFC822 Internet. It
is impossible to tell by inspecting a user's address whether
the user receives RFC822 mail or X.400 mail.
Since these addresses appear to be standard RFC822
addresses, mail managers, mailing list managers, host
administrators, and users expect to be able to simply send
mail to "postmaster@domain" and having the message be
delivered to a responsible party. When an RFC1327 mapping
rule exists, the X.400 address elements corresponding to the
left-hand-side "postmaster" are "Surname=Postmaster" (both
1984 and 1988) and "CommonName=Postmaster" (1988 only).
However, neither the X.400 protocols, North America X.400
Implementor's Agreements [7], nor the European X.400
Implementor's Agreements [8] require that
"Surname=Postmaster" and "CommonName=Postmaster" be
supported. (Supporting these addresses is recommended in
X.400 (1988)).
For mapped X.400 domains which do not support the postmaster
address(es), this means that an address such as
"user@some.place.zz" might be valid, yet mail to the
corresponding address "postmaster@some.place.zz" fails.
This is frustrating for remote administrators and users, and
can even prevent operational problems from being
Cargille Expires May 18, 1993 [Page 2]
DRAFT X.400 Postmaster Convention Nov 1992
communicated and resolved. In this case, the desired
seamless integration of the Internet RFC822 mail world and
the mapped X.400 domain has not been achieved.
The X.400 mail managers participating in the Cosine MHS
Project discussed this problem in a meeting in June 1992
[9]. The discussion recognized the need for supporting the
postmaster address at any level of the address hierarchy
where these are user addresses. However, in the end, the
Cosine MHS Managers only recommended support of the
postmaster address Surname and Common Name at all levels of
the address hierarchy down to the Organization level--that
is, only for addresses of the form
C=xx; ADMD=someadmd; S=postmaster
C=xx; ADMD=someadmd; O=org; S=postmaster
C=xx; ADMD=someadmd; PRMD=someprmd; S=postmaster
C=xx; ADMD=someadmd; PRMD=someprmd; O=org; S=postmaster
While there is value in supporting postmaster addresses down
to the Organization level, this does not solve the entire
problem of consistent email management between the Internet
RFC822 world and mapped X.400 mail domains. Specifically,
there are cases where a user's RFC822-style address maps
into an X.400 address containing attributes below
Organization, such as Organizational Units. Again, RFC822
community members have no idea what the X.400 representation
of the address is, nor should they need to know. However,
they expect that if they can send mail to (for example)
"user@some.place.zz", then they should also be able to mail
"postmaster@some.place.zz". If they cannot, then the
desired seamless integration of the X.400 and RFC822 mail
worlds has not been realized, and the quality of service has
broken down.
3. Proposed Solution
To fully achieve the desired seamless integration of email
domains for which RFC1327 mapping rules have been defined,
the following convention must be followed,
If there are any valid addresses of the form
"user@domain", then the address "postmaster@domain"
must also be valid.
To express this in terms of X.400: For every X.400 domain
for which an RFC1327 mapping rule exists, if any address of
the form
Surname=User; <Other X.400 Address Elements>
is a valid address, then the address
Cargille Expires May 18, 1993 [Page 3]
DRAFT X.400 Postmaster Convention Nov 1992
Surname=Postmaster; <Same X.400 Address Elements>
must also be a valid address. If the X.400 system is
running X.400(1988), then the address
CommonName=Postmaster; <Same X.400 Address Elements>
must also be supported.
To remain consistent with RFC822, "Mail sent to that address
is to be routed to a person responsible for the site's mail
system or to a person with responsibility for general site
operation." [10]
4. References
[1] RFC822
[2] RFC1173
[3] X.400 (1984)
[4] X.400 (1988)
[5] RFC1327
[6] presently draft-ietf-x400ops-mgtdomains-ops-02.txt
[7] NIST X.400 Implementors Agreements
[8] EWOS X.400 Implementors Agreements
[9] Minutes from June 1992 Cosine MHS Managers Meeting
[10] RFC822, direct quote
Cargille Expires May 18, 1993 [Page 4]