Administering Mail and Messaging

Channel delivery

The delivery agent that is associated with a mail channel is equivalent to a sendmail delivery agent definition in sendmail.cf. When a message's address is successfully matched by a channel table, then the ruleset 0 triple is resolved for that address, including the delivery agent name. Therefore, there each channel has a separate delivery agent, defined by the M configuration file command (see ``M: define mailer''). The name specified to the Mail Manager for the channel is used as the symbolic name of the delivery agent.

NOTE: There is not a one-to-one mapping of channels to delivery agent definitions in sendmail.cf, since sendmail has special, internally defined delivery agents which may also be defined within sendmail.cf.

The Mail Manager offers the following types of delivery programs:

/etc/mail/slocal
A program which performs final, local delivery, with support for user-tailorable $HOME/.maildelivery files for mail processing. See the slocal(1) and maildelivery(4) manual pages for details.
SMTP
Simple Mail Transfer Protocol.
/usr/bin/uux
The UNIX to UNIX copy command, which transfers data between UUCP systems. See uucp(1bnu).
/etc/mail/multihome
A program routes mail addressed to users in virtual domains to the correct physical users on the system.
Custom channel
A custom channel whose pathname you must specify. By default the path to this program begins with /etc/mail, but any location may be specified.

The delivery program is equivalent to the ``P='' equate, which is specified in a delivery agent definition in sendmail.cf. Additional equates may be configured by the Mail Manager. Of particular importance are the ``A='', ``R='', and ``S='' equates.

The ``A='' equate specifies the command line invocation of the delivery program, and specifies the arguments for the program, and may be defined using the h and u macros. A channel often uses these macros to pass information to the delivery program, and what values these macros have depends upon the type of table used by the channel.

The ``R='' and ``S='' equates specify how the sender and recipient addresses will be re-written for both the header and envelope of the message. The Mail Manager offers three types of re-writing rulesets, which correspond to SMTP (RFC822 compliant), UUCP (RFC976 compliant), and local delivery.

Both the program arguments equate (A=) and the address re-writing equates (``S='' and ``R='') must be defined to fit the delivery program chosen. In general, the Mail Manager will create defaults for these values. However, it is recommended that those administrators who will wish to create customized channels become familiar with the delivery agent definition in sendmail.cf.

See ``Mail delivery channels'' for more information on configuring mail channels using the Mail Manager. For information on the delivery agent M configuration file command, see ``M: define mailer''.