Steve,

 

Although the Bindings will populate with all IP Addresses that are assigned to your Network Interface in Windows if you go to SETTINGS > BINDINGS and click on the PORTS tab you can uncheck the Port Bindings for any IP Addresses you don't want those individual services to function on. Once complete your BINDINGS tab should show 0 Ports for the IP Addresses you don't want used by SmarterMail.

 

Then under SETTINGS > PROTOCOLS you can set your default SMTP Out to a specific IP (you can also assign a different IP on a domain basis under MANAGE > %DomainName% > SECURITY and changing the Outbound IPv4 & IPv6 Addresses (if "Unassigned" it will use the global default you set in Protocols).

 

(I don't think you need to restart the Smartermail Service but you may have STOP & START any protocols in MANAGE > TROUBLESHOOTING > SERVICES...but just to be safe I would restart the Smartermail Service from the cmd prompt or in Windows Services if you can.)