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sendmail Desktop Reference

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The sendmail.cf File
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2.2 Delivery Agent Equates

The general form of a delivery agent's declaration looks like this:


, ...

In this section we list and describe each equate , where only the first letter of each is recognized (that is, Argv= is the same as A= ).

A= argv0 argv1 ...

Lists the delivery agent's command-line arguments. The delivery agent speaks SMTP only if $u is absent from those arguments. The special symbolic argv0 names IPC and LPC reference internal sendmail code.

C= ISO-8859-1

Uses the ISO-8859-1 character set in the MIME Content-Type: header (see §30.4.2). Applies to messages received from this delivery agent. Supersedes the DefaultCharSet option.

D= /var/run:/tmp

Sets the paths for execution of the prog delivery agent to /var/run first, and if it cannot chdir (2) into that directory, then to /tmp (see §30.4.3).

E= \r

Specifies the end-of-line characters to be a carriage-return newline pair. Those characters are generated by sendmail for outgoing messages and recognized by sendmail for incoming messages. The default is \r\n for SMTP and \n otherwise (see §30.4.4).

F= flags

Lists flags that describe a delivery agent's behavior (fully listed in the next section, "Delivery Agent F= Flags").

L= 512

Limits the length of text lines in the body of a mail message to 512 characters (see §30.4.6).

M= 1000000

Limits the total size (header and body combined) of messages handled by the delivery agent to one million characters.

N= 5

Says to re- nice (2) the delivery agent by 5 (see §30.4.8).

P= /usr/bin/uux

Says to execute /usr/bin/uux as the delivery-agent program (see §30.4.9). Special symbolic paths can also be used: [ IPC ] makes a network connection and speaks SMTP; [ FILE ] appends the message to a file; and [ LPC ] is useful for tracking down mail problems.

R= rset or R= eset / hset

Lists the rewriting rule set names or numbers for the recipient. A single name or number is applied to both envelope and header rewriting. Two names or numbers, separated by a slash, applies the leftmost to the envelope and the rightmost to headers (see §30.4.10).

S= rset or R= eset / hset

Lists the rewriting rule set names or numbers for the sender. Particulars are the same as for R= above (see §30.4.11).

T= DNS/RFC822/X-Unix

Sets the type tags used in the DSN diagnostic returns for this delivery agent. The type tag for the Reporting-MTA: field is DNS ; the type tag for the Final-Recipient: field is RFC822 ; and the type tag for the Diagnostic-Code: field is X-Unix (see §30.4.12).

U= nullmail:nullgroup

Specifies that sendmail should become the user nullmail and the group nullgroup before executing the delivery agent. If the :nullgroup is omitted, it is found in the passwd (5) file entry for nullmail (see §30.4.13).