An email domain is a set of email accounts that reside on a particular email server. The email domain name is the portion of the user’s email address following the “@” symbol.

FortiMail units can be configured to protect email domains (referred to as “protected domains” in this Administration Guide) by defining policies and profiles to scan and relay email that is incoming to or outbound from protected domains.

If the FortiMail unit is operating in gateway mode or transparent mode, there is one local email domain that represents the FortiMail unit itself. If the FortiMail unit is operating in server mode, protected domains reside locally on the FortiMail unit’s built-in email server.

For information about creating protected domains, see “Configuring protected domains”.

In transparent mode, each network interface includes a proxy and/or implicit MTA that receives and relays email. By default, the proxy/implicit MTA responds to SMTP greetings (HELO/EHLO) using the host name of the SMTP server of the protected domain. For information about configuring the proxies, see “Configuring proxies (transparent mode only)”. For information on configuring the SMTP greeting, see “Configuring protected domains”.