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Chapter 30 |
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30. Delivery Agents
Contents:
Configuration File Syntax
The Symbolic Name
m4 Configuration Syntax
The Equates
Internally Defined Names
How Executed
Pitfalls
Alphabetized F= Flags
The
sendmail
program does not perform the actual delivery of mail.
Instead, it calls other programs (called mail delivery agents) to perform
that service. Because the mechanics of delivery can vary so widely
from delivery agent to delivery agent,
sendmail
needs a great
deal of information about each delivery agent.
Each
sendmail
M
configuration-file
command defines a mail delivery agent
and the information that
sendmail
needs.
30.1 Configuration File Syntax
Like all
sendmail.cf
commands, the
M
mail delivery agent
command must begin a line. One typical such command looks like
this:
delivery program
command line
Mlocal, P=/bin/mail, F=rlsDFMmnP, S=10, R=20, A=mail -d $u
flags
sender/recipient rules
This
M
configuration command is composed of six parts: a symbolic name
followed by five equates,
each separated from the others by commas. Spaces
between the parts are optional. The specific syntax of the mail delivery
agent command is
Msymname, equate, equate, ...
The letter
M
always begins the delivery agent definition,
followed by a symbolic name (the
symname
) of your choosing and a
comma-separated list of delivery agent equates.
Only the
P=
and
A=
equates are required. The others
are optional.
The comma following the symbolic name is optional. As long as there is a space following the symbolic name, sendmail parses it correctly. The comma should, however, always be included for improved clarity. [1]
[1] SunOS 4.1.2's sendmail does not properly support freezing if the comma is present.
In the following, the first example includes the comma, and the second omits it. Both are parsed by sendmail in exactly the same way:
Mlocal, P=/bin/mail, F=rlsDFMmnP, S=10, R=20, A=mail -d $u Mlocal P=/bin/mail, F=rlsDFMmnP, S=10, R=20, A=mail -d $u
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| 29.11 Pitfalls |
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30.2 The Symbolic Name |