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draft-ietf-x400ops-postmaster-01.txt
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INTERNET DRAFT March 1993
Postmaster Convention for X.400 Operations
Mon Mar 22 23:26:25 CST 1993
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>.
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 RFC1123 (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 September 22, 1993 [Page 1]
DRAFT X.400 Postmaster Convention March 1993
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 element corresponding to the left-hand-side
"postmaster" is "Surname=Postmaster" (both 1984 and 1988).
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 prevent
operational problems from being 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.
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DRAFT X.400 Postmaster Convention March 1993
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, the group only required supporting the
postmaster address down to certain levels of the O/R Address
tree. This approach solved part of the problem, but not all of
it. A more complete solution is required.
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
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. (Note that CommonName=Postmaster will
not be generated by RFC1327 mappings, but it is recommended in
the 1988 X.400 standard).
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]
3.1. Software Limitations - Fallback Solution
In the discussion of this issue, it was pointed out that not all
end hosts can support mail forwarding to a central postmaster
mailbox on a remote host. For example, this could be the case on
a a personal computer with limited software. In this case,
either the postmaster address cannot be supported on the end
host, or a different postmaster address must be created and read
on each end host. Creating and maintaining multiple postmaster
mailboxes is considered unacceptable due to the great
administrative overhead required--most likely, such multiple
Cargille Expires September 22, 1993 [Page 3]
DRAFT X.400 Postmaster Convention March 1993
mailboxes would not be read in a timely manner. Therefore, the
following fallback solution is approved:
If there are any valid addresses of the form
"user@host.domain" where the mail software in use does
not support forwarding postmaster mail to a central
mailbox, then the address "postmaster@domain" must be
valid.
As above, the X.400 address derived by mapping
"postmaster@domain" via RFC1327 must also be valid. If X.400(88)
is used, CN=postmaster must also be supported.
4. References
[1] RFC822
[2] RFC1123
[3] X.400 (1984)
[4] X.400 (1988)
[5] RFC1327
[6] presently draft-ietf-x400ops-mgtdomains-ops-04.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 September 22, 1993 [Page 4]