SMTP_FORWARD

This configuration variable defines the Internet hostname (not the IP address; this variable must contain a fully qualified domain name) of the server to which all outgoing SMTP mail should be forwarded for delivery. This can be any machine with SMTP software that will accept mail from your machine. If you are running the MS Mail SMTP gateway product as your SMTP forwarding host, you should point SMTP_FORWARD to the "smart host" defined in the MS Mail configuration rather than to the MS Mail gateway itself.