Introduction
Some server administrators prefer that all outbound email be handled by an external server or a third-party service. If you would like all email routed through another server, you can set up your server to use a smarthost.
Procedure
To set up a server-wide smarthost, go to WHM's Home »Service Configuration »Exim Configuration Manager and search for the option, "Smarthost Support."
Enter an asterisk (*) and a space, followed by the value of the smarthost. This will be the server that is routing all email for the domains sending outbound email.
If you know the IP of the smarthost server, you could use this syntax:
* 192.0.2.1
Or if you know the hostname of the smarthost, you could use this syntax:
* sendingserver.smarthost.com