Sometimes it is convenient to configure PMDF to route mail not for the
local host, or a group of local machines, to a central machine and
leave it up to that machine to deal with the mail, perhaps relaying it
to the outside world or other local machines, or perhaps even
gatewaying it into other mail systems. The following example
configuration, Example 2-3 , illustrates doing just this. The local
host is HOSTA.ACME.COM and two other local machines, HOSTB.ACME.COM and
HOSTC.ACME.COM, are recognized. Mail for either of those two machines
is sent via a tcp_local channel (SMTP over TCP/IP) to those hosts. All
other mail not for HOSTA, HOSTB, or HOSTC is sent via another SMTP over
TCP/IP channel, named tcp_gateway, to the host MAILHUB.ACME.COM. A
"match-all" rule is used to direct all mail not for HOSTA,
HOSTB, or HOSTC to that channel. (The match-all rule is described in
Section 2.2.4.3 .) The daemon keyword is used with the
tcp_gateway channel; the usage of this keyword with SMTP over TCP/IP
channels is discussed in Section 2.3.4.80 . It tells the channel to route
messages queued to it through the host MAILHUB.ACME.COM.
Example 2-3 Routing messages to a central machine
! ! Rewrite rules for the local host/cluster ! HOSTA $U@HOSTA.ACME.COM HOSTA.ACME.COM $U@HOSTA.ACME.COM ! ! Rewrite rules for some internal systems ! HOSTB.ACME.COM $U%HOSTB.ACME.COM@TCP-DAEMON HOSTC.ACME.COM $U%HOSTC.ACME.COM@TCP-DAEMON ! ! Use a match all rule to route everything ! else to the MAILHUB.ACME.COM ! . $U%$H@MAILHUB.ACME.COM$A l HOSTA.ACME.COM tcp_local smtp single_sys mx TCP-DAEMON tcp_gateway smtp mx daemon router MAILHUB.ACME.COM