SMTP, IHS and the Plug-in

I currently have a Domino server in my DMZ that handles SMTP traffic and hosts some user’s mail files to be accessed via iNotes. I also have two clustered mail servers on our internal network that hosts all user’s mail files. I’d like to replace the server in the DMZ with an IBM HTTP Server running the plug-in so that users on the outside can access the IHS box and get to their iNotes mail on the internal servers. That part is easy. The question I have is, how do I handle the SMTP traffic? Can I somehow use the plug-in to route SMTP messages to the internal servers or will I still have to have an SMTP server out in the DMZ?

Also, has anyone got Sametime working through the plug-in?