RFC 976 (rfc976) - Page 2 of 12

UUCP mail interchange format standard

RFC 976                                                    February 1986
UUCP Mail Interchange Format Standard


   those two standards.  In addition, should the ARPA community change
   these standards at a later time, we intend to change our standards to
   remain compatible with theirs, given a reasonable time to upgrade
   software.

   This document specifies an interpretation of RFC-822 and RFC-920 in
   the UUCP world.  It shows how the envelope should be encoded, and how
   UUCP routing is accomplished in an environment of mixed
   implementations.

2.  Basics

   Messages can be divided into two parts: the envelope and the message.
   The envelope contains information needed by the mail transport
   services, and the message contains information useful to the sender
   and receiver.  The message is divided into the header and the body.
   Sometimes an intermediate host will add to the message (e.g. a
   Received line) but, except in the case of a gateway which must
   translate formats, it is not expected that intermediate hosts will
   change the message itself.  In the UUCP world, the envelope consists
   of the "destination addresses" (normally represented as the argument
   or arguments to the rmail command) and the "source path" (normally
   represented in one or more lines at the beginning of the message
   beginning either "From " or ">From ", sometimes called "From_
   lines".)  The RFC-822 header lines (including "From:" and "To:") are
   part of the message, as is the text of the message body itself.

   UUCP uses short host names, such as "ucbvax", at and below the
   transport layer.  We refer to these names as "6 letter names",
   because all implementations of UUCP consider at least the first 6
   letters significant.  (Some consider the first 7 or the first 14
   significant, but we must use the lowest common denominator.) UUCP
   names may be longer than 6 characters, but all such names much be
   unique in their first 6 letters.  RFC-920 domain names, such as
   "ucbvax.Berkeley.EDU", are called "domain names." The two names are
   different.  Upper and lower case are usually considered different in
   6 letter names, but are considered equivalent in domain names.  Names
   such as "ucbvax.UUCP", consisting of a 6 letter name followed by
   ".UUCP", previously were domain style references to a host with a
   given 6 letter name.  Such names are being phased out in favor of
   organizational domain names such as "ucbvax.Berkeley.EDU"








Horton