Configuring MUAs to use FortiMail
Configure the email clients of local and remote email users to use the FortiMail unit as their outgoing mail server (SMTP)/MTA. For local email users, this is the FortiMail IP address, 192.168.1.5. For remote email users, this is the virtual IP address on the wan1 network interface of the FortiGate unit that maps to the FortiMail unit, 10.10.10.1 or fortimail.example.com.
Also configure email clients to authenticate with the email user’s user name and password for outgoing mail. The user name is the email user’s entire email address, including the domain name portion, such as email@example.com.
If you do not configure the email clients to authenticate, email destined for other email users in the protected domain may be accepted, but email outgoing to unprotected domains will be denied by the access control rule.