[quote user="caraudiovideo"]Thanks, that is leading me in the right direction. Would it be easier for me to simply set up multiple instances of Mercury? I only have 1 external IP and can only forward traffic to one internal IP.
instance1: domain1.com on ip 192.168.1.2
instance2: domain2.com on ip 192.168.1.2[/quote]
Multiple instances of Mercury is required but the servers should be running on different ports if all are on the same system. One of the servers would be the gateway server and puts mail into domain mailboxes for the domains not served on the system. The other systems would get the mail via SMTP to the different SMTP ports (i.e. 8025, 2525, 1025, etc) using WSMTPEx.exe or pulled from the gateway system via MercuryD. I like the push via WSMTPEx but the pull via MercuryD works as well as long as you use the X-Envelope-To: header for mail delivery.