RFC 976 (rfc976) - Page 2 of 12
UUCP mail interchange format standard
Alternative Format: Original Text Document
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
