Utilities: Administration: Server: Server Settings: Network Settings: Receive Email
Forward mail IP address
Optionally forward non-ListManager mail to another SMTP server.
This setting allows ListManager to coexist with another SMTP server on the same machine and IP address.
For instance, if the machine you want to run ListManager on has a mail server running on it (i.e. Sendmail or Post.Office) and you want this machine to continue running a mail server, this setting will allow ListManager to coexist with your mail server.
Mail sending and receiving from both ListManager and your regular mail server is unaffected. In this way, both ListManager and your mail server can coexist on the same machine.
For this setting, specify the TCP/IP address of the receiving mail server.
For example: "127.0.0.1" forwards non-ListManager mail to an SMTP server running on the same machine.
Important Note: Because ListManager blindly forwards all non-ListManager mail to the mail server listed here, the receiving email server should have rules so it does not automatically trust any mail received from ListManager. Otherwise, the receiving mail server could become an open relay. ListManager by itself cannot be an open relay.
See Mail Server Coexistence for more information.
Forward mail port
Specifies the port ListManager should forward non-ListManager mail. "25" is the standard SMTP port; if ListManager is coexisting on the same IP address as another mail server, you will need to configure that mail server to listen to another port (e.g., 26). You may then specify the port number here.
More
1. Server Settings: Network Settings: Receive Email
2. Server Settings: Network Settings: Deliver Email
3. Server Settings: Network Settings: Relay Hosts
4. Server Settings: Network Settings: Ports
5. Server Settings: Network Settings: DNS