This is my first time setting up an IronPort. The model we have is a C170. We only have 1 interface connected in our network. We don't have a DMZ setup and our network is flat (no routing/vlans). When I tried to configure a 2nd listener, it tells me that port 25 is already used by the 1st listener. Is ther a way to use a single interface to send and receive mail? Our network is behind a ASA 5505. Or if you have a document you can send me to, that will help too.