108 lines
4.2 KiB
Plaintext
108 lines
4.2 KiB
Plaintext
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.\" Copyright (c) 1980, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)mail7.nr 8.1 (Berkeley) 6/8/93
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.\"
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.sh 1 "Format of messages"
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.pp
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This section describes the format of messages.
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Messages begin with a
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.i from
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line, which consists of the word
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.q From
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followed by a user name, followed by anything, followed by
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a date in the format returned by the
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.i ctime
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library routine described in section 3 of the Unix Programmer's
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Manual. A possible
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.i ctime
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format date is:
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.(l
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Tue Dec 1 10:58:23 1981
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.)l
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The
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.i ctime
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date may be optionally followed by a single space and a
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time zone indication, which
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should be three capital letters, such as PDT.
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.pp
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Following the
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.i from
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line are zero or more
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.i "header field"
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lines.
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Each header field line is of the form:
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.(l
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name: information
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.)l
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.i Name
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can be anything, but only certain header fields are recognized as
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having any meaning. The recognized header fields are:
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.i article-id ,
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.i bcc ,
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.i cc ,
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.i from ,
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.i reply-to ,
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.i sender ,
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.i subject ,
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and
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.i to .
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Other header fields are also significant to other systems; see,
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for example, the current Arpanet message standard for much more
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information on this topic.
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A header field can be continued onto following lines by making the
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first character on the following line a space or tab character.
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.pp
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If any headers are present, they must be followed by a blank line.
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The part that follows is called the
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.i body
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of the message, and must be ASCII text, not containing null characters.
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Each line in the message body must be no longer than 512 characters and
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terminated with an ASCII newline character.
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If binary data must be passed through the mail system, it is suggested
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that this data be encoded in a system which encodes six bits into
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a printable character (i.e.: uuencode).
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For example, one could use the upper and lower case letters, the digits,
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and the characters comma and period to make up the 64 characters.
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Then, one can send a 16-bit binary number
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as three characters. These characters should be packed into lines,
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preferably lines about 70 characters long as long lines are transmitted
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more efficiently.
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.pp
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The message delivery system always adds a blank line to the end of
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each message. This blank line must not be deleted.
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.pp
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The UUCP message delivery system sometimes adds a blank line to
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the end of a message each time it is forwarded through a machine.
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.pp
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It should be noted that some network transport protocols enforce
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limits to the lengths of messages.
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