Currently (unless I'm missing something) the Outgoing gateways are by IP address only.  Recently the outbound server I've been using changed their IP address.  All outbound mail was stopped until I figured out what had happened.  If you could input the outbound gateway by server name this would have been avoided. The outbound mail service provider says they're under no obligation to notify users of IP changes.  So unless I get a bounce back or someone calls there's nothing to alert me to the problem.