Just finished installing a mail server. Using postfix, courier-imap, virtual domains via mysql tables, spam assassin, postfix admin and finally squirrel mail. Making the gory linux stuff got working was harder than it should have been. Probably because of the fedora core 4 distro I used. Authdaemon woes. Convoluted configuration files and compilation
options. Next time I will try the very same system with a debian install and see if it really can be done with a couple of apt-get commands.
But now that things work it seems to be very nice. ClamAV needs to get added at some point, and there are probably twelve million add ons for squirrel mail etc. But overall it works like a charm.
And running this postfix system means one less Microsoft exchange server.