I'm using Sendmail on my Debian box. It doesn't seem to support virtual users/host names without setting up a user for each actual mailbox. I'd rather have one of those database systems to hold my mail. Also, being I don't need Sendmail I'd rather not deal with its complexities.
So, there's smail, exim, and others to look at. Now it's off to figure out what the difference is between them, and choose the best one for my configuration. Then, to get a good pop3(/imap) client.
Any ideas? I'd like to hear more about this subject.