Computer mail meeting notes
RFC 805

Document Type RFC - Unknown (February 1982; No errata)
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Network Working Group                                          J. Postel
Request for Comments:  805                                           ISI
                                                         8 February 1982

                      Computer Mail Meeting Notes


   A meeting was held on the 11th of January 1982 at USC Information
   Sciences Institute to discuss addressing issues in computer mail.
   The attendees are listed at the end of this memo.  The major
   conclusion reached at the meeting is to extend the
   "username@hostname" mailbox format to "username@host.domain", where
   the domain itself can be further structured.


   The meeting opened with a brief discussion of the objectives of the
   meeting and a review of the agenda.

      The meeting was called to discuss a few specific issues in text
      mail systems for the ARPA Internet.  In particular, issues of
      addressing are of major concern as we develop an internet in which
      mail relaying is a common occurance.  We need to discuss
      alternatives in the design of the mail system to provide high
      utility at reasonable cost.  One scheme suggested is to create
      "mail domains" which are another level of addressing.  The ad hoc
      scheme of source routing, while effective for some cases, is seen
      to lead to some problems.  A key test of addressing schemes is the
      procedure for sending copies of a reply to a message to the people
      who received copies of the original message.  The key reference
      documents for the meeting were RFCs 788, 799, and 801.

   Jon Postel gave a brief review of the NCP-to-TCP transition plan (RFC
   801).  The emphasis was on mail, the internet host table, and the
   role of a Host Name Server.

   The major part of the meeting was devoted to a wide ranging
   discussion of the general mailbox identification problem.  In
   particular, the notion of a hierarchial structure of name domains was
   discussed, and the issues associated with name servers were discussed
   including the types of information name servers should provide.

Name Domains

   One of the interesting ideas that emerged from this discussion was
   that the "user@host" model of a mailbox identifier should, in

Postel                                                          [Page 1]

Computer Mail Meeting Notes                              8 February 1982

   principle, be replaced by a "unique-id@location-id" model, where the
   unique-id would be a globally unique id for this mailbox (independent
   of location) and the location-id would be advice about where to find
   the mailbox.  However, it was recognized that the "user@host" model
   was well established and that so many different elaborations of the
   "user" field were already in use that there was no point in persuing
   this "unique-id" idea at this time.

   Several alternatives for the structuring and ordering of the
   extensions to the "host" field to make it into a general
   "location-id" were discussed.

      These basically involved adding more hierarchical name information
      either to the right or the left of the @, with the "higher order"
      portion rightmost or leftmost.  It was clear that the information
      content of all these syntactic alternatives was the same, so that
      the one causing least difficulty for existing systems should be
      chosen.  Hence it was decided to add all new information on the
      right of the @ sign, leaving the "user" field to the left
      completely to each system to determine (in particular to avoid the
      problem that some systems already use dot (.) internally as part
      of user names).

   The conclusion in this area was that the current "user@host" mailbox
   identifier should be extended to "user@host.domain" where "domain"
   could be a hierarchy of domains.

      In particular, the "host" field would become a "location" field
      and the structure would read (left to right) from the most
      specific to the most general.

         For example: "Postel@F.ISI.IN" might be the mailbox of Jon
         Postel on host F in the ISI complex of the Internet domain.

      Formally, in RFC733, the host-indicator definition rule would

         host indicator = ( "at" / "@" ) domains

         domains = node / node "." domains

            Note only one "at" or "@" is allowed, and that the domains
            form a hierarchy with the most general in scope last.

            And note that the choice of domain names must be
            administratively controlled and the highest level domain
            names must be globally unique.

Postel                                                          [Page 2]

Computer Mail Meeting Notes                              8 February 1982

      The hierarchial domain type naming differs from source routing in
      that the former gives absolute addressing while the latter gives
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