Anyway, the documentation is a big read, and it's not due to a lack of knowledge, or an unwillingness to help from users here that's the cause of the lack of response, setting up a mail server is no easy feat - well it wasn't in 10.3 Server, and when I read the 10.4 manuals it didn't seem any easier. Basically someone would be posting the full contents of the manual here to get you through the setup. Even then it would have to assume that the installation and setup was completed correctly - the software installs easily, it's the initial setup that still frightens me. i've heard it's a lot better in 10.5 and 10.6.
10.5 is easier. 10.6 is a doddle. If you can buy yourself a copy of 10.6 server, use that because it's a piece of cake.
I'd recommend for 10.5 Server over anything else (including Apple's documentation), the
Lynda.com training. Yes, that's 11 hours of video, but it sets you right up for everything. You can dip in to the sections you need, but I'd completely recommend starting at the beginning and working your way through. This way you'll understand the importance of DNS working correctly on the system (if you don't get it right first time you can be looking - potentially - at a complete reinstall of the OS).
Just as Ballmer said "Developers! Developers! Developers!", I - and Lynda.com, the manuals and all the OS X pros I know - say "DNS! DNS! DNS!".
Alternatively, look at 10.6. I'm evaluating the upgrade path for our couple of racks of Xserves, and have been hugely impressed by how simple the setup can be. It's just in a different league from anything else on the market, but the proper config ability is still there for the admins who need the raw customisation.
All in all, what you get back from OS X Server is what you put in. While it sounds like people are fobbing you off, they're really not. You can't do a thorough job without going through documentation (and/or something like the Lynda.com training) - and the posters above are right - if we listed what exactly to do, we'd end up quoting the manuals.
Best of luck with your quest for Mail, and if you do have any issues with specific parts of the configuration, I know we'll be happy to help.
🙂