A Smart Host is a SMTP server that will accept mail from another server and then deliver the mail for that server.
For example, server1 is setup to use server2 as a smart host.
Anytime someone sends e-mail on server1 it is automatically relayed to server2 regardless of the MX entrys for the domain.
Server2 then accepts this message, looks up the proper delivery host/IP and attempts to deliver the message to that host.
To configure a smart host, create
and add the following lines.
Be sure to change to the hostname or ip of the smart host server:
driver = manualroute
domains = !+local_domains
transport = remote_smtp
route_list = * host.name.of.smart.host.server
Thats it, watch the logs for a bit to make sure it’s working!