RFC 1648 (rfc1648) - Page 2 of 4

Postmaster Convention for X

RFC 1648              X.400 Postmaster Convention              July 1994


   addresses, and these email domains are a logical extension of the RFC
   822 Internet.  It is impossible to tell by inspecting a user's
   address whether the user receives RFC 822 mail or X.400 mail.

   Since these addresses appear to be standard RFC 822 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 RFC
   1327 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 other regional X.400
   implementor's agreements 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 ""
   might be valid, yet mail to the corresponding address
   "" 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 RFC 822 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 [8].  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 RFC 1327 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 RFC 1327 mapping rule exists, if any address of the form

      Surname=User; 




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