revised postmaster document

[Allan Cargille <[e-mail]>]

Hi, as promised, here's the revised postmaster document.  (Yes, it's
still Monday -- barely! ;-)   I will wait until the end of Tuesday to
receive quick comments about typos, etc, and then submit it to the
Internet Draft archives.

The one technical change appears in the new section 3.1 below.  Several
paragraphs were deleted at the end of section 2.  These changes were
made based on comments received at the Jan 1993 Managers meeting.

Cheers,

allan

======================================================================




          INTERNET DRAFT                                         March 1993


                     Postmaster Convention for X.400 Operations

                            Mon Mar 22 23:26:25 CST 1993


                                  C. Allan Cargille
                               University of Wisconsin
                             [e-mail]





          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
          <[e-mail]>.

          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
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          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).










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          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
          "[e-mail]" might be valid, yet mail to the
          corresponding address "[e-mail]" 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


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          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
              "[e-mail]" 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





















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