Administering Mail and Messaging

Managing mail channels

In UnixWare, sendmail has been configured to use mail channels to deliver mail. A mail channel is logically composed of two components:

a table whose data determines what messages will be delivered by the channel
an agent which performs the actual delivery

All messages are processed by the configured channels. The first channel table that produces a successful lookup and match of a message's address causes its associated delivery agent to be used for delivery of that message. Therefore, the order of channels is significant. Any address which does not resolve to a channel (the address does not find a match in any channel table) is considered undeliverable, and ``bounces'' back to the sender.

For example, suppose your machine is able to connect to two machines via UUCP, and that these machines are listed in the /etc/uucp/Systems file. Furthermore, you wish any mail to these machines to be sent via UUCP, using the uux(1bnu) command. A mail channel can be configured which uses the Systems file as the table, and uux as the delivery agent. This is exactly how the Mail Manager creates its UUCP channel.

``UnixWare mail channels'' illustrates the relationship between a mail host and the five mail channels supported by UnixWare.

UnixWare mail channels