So. I wrote earlier about configuring sendmail imapd and Apache through these articles. I also managed to get SSL working in Apache on my own (though Internet Explorer doesn't work with it, Chimera, Mozilla, Netscape, OmniWeb does).
Anyway, as I said you need imapd to be configured without ssl, which can be accomplished through either compiling a new one with BOTH ssl and no ssl. I chose to create two imapds however. Mostly for simplicity, and avoiding problems. That way you can use the standard instructions in the oreilly article on imapd with ssl, and use the standard config coming with imapd when compiling without ssl.
I now got my own domainname an industrialstrength Apache serving virtual domains so that webmail.mydomain.com takes me directly to the webmail login page and www.mydomain.com shows the standard webpage. All on the same machine. YEEEHAA!
Mail is sent to firstname.lastname@example.org
(mydomain.com is NOT my domain, just used it in this note for security reasons)
A note on Squirrelmail was what I was supposed to do though.
Squirrelmail is very easy to configure and doesn't require a database backend such as MySQL. Squirrelmail is a bit ugly though in my opinion. So I went looking for another webmail-system, and guess what? I found something much better. It does however use MySQL as a backend and got LOADS of features I will probably not use such as Calendars, Todo lists etc. It's still much nicer.
It's name is Twiggi. You can get it here: http://twiggi.sourceforge.net
First I'd advice you to install MySQL though. It's really not that difficult if you go here and follow the instructions: http://www.entropy.ch/software/macosx/mysql/
Also you must have php working in Apache. There's an article on that here on oreilly.
You'll probably run into some trouble, I know I did. Most of the time though, just take it easy and have patience. You'll get it running. If all else fails - delete everything you installed and start over.