ZCS Administrator Guide 8.0

Network Edition

Sending Non Local Mail to a Different Server

You can configure Postfix to send nonlocal mail to a different SMTP server, commonly referred to as a relay or smart host.

A common use case for a relay host is when an ISP requires that all your email be relayed through a designated host, or if you have filtering SMTP proxy servers.

The relay host setting must not be confused with Web mail MTA setting. Relay host is the MTA to which Postfix relays non-local email. Webmail MTA is used by the Zimbra server for composed messages and must be the location of the Postfix server in the Zimbra MTA package.

Configure Relay MTA for external delivery from the administration console, Global Settings>MTA page.

Important: Use caution when setting the relay host to prevent mail loops.