David,
What the heck are you doing on this board. I couldn't believe it when I saw your name. What a small world. Good to see you're going for a Linux server, and a good one at that. I've been researching these Linux GPL server distributions for a while now as I'm trying to set up a small LAN with a server which can also provide a secure Internet gateway for the LAN and a DMZ where I can host a small family web site (for all those baby pics). Unfortunately, I'm not planning on setting up a mail server at the moment, but will when I upgrade my server hardware. The hardware I'm using now is only enough for a category 1 server. However, I have a friend Larry who has set up a mail server and has been using it for quite some time. I believe he's still using the previous server version. He may be able to give you some quick pointers and he may even answer your post on this board as he is an avid user. In any event, I'll forward your inquiry to him at his e-mail address.
Good luck with your setup. I just loaded SME server V5 and just about to configure everything. You'll probably see some posts from me soon, in addition to the one I made few days ago. I may have used my office e-mail address on that post.
Scott