An SMTP gateway definition inside AfterLogic XMail Server can be followed by a set of configuration options, that are in the form of a comma-separated VAR=VAL or FLAG definitions. Currently defined options are:
If set to 1, instruct AfterLogic XMail Server to try to establish a TLS session with the remote host (by the means of a STARTTLS SMTP command). If set to 2, AfterLogic XMail Server will try to establish a TLS session, but it will fail if not able to do so (the remote server does not support STARTTLS, or reject our attempt to negotiate the TLS link).
Sets the IP address of the network interface that should be used when connecting to the remote host. This configuration should be used carefully, because AfterLogic XMail Server will fail if the selected IP of the interface does not have a route to the remote host using such IP.