OK, that felt like 1998. I had expected that a full-blown Postfix+Dovecot with IMAP, POP3, with and without SSL and TLS, on Maildirs with virtual users and DSPAM configured would be a single apt-get install.

Anyway, what's a guide doing asking users to choose between four flavors of protocols? Just enable them all. Maildirs/mbox? Mbox is ancient, no possible reason to setup new accounts using that. And the biggest WTF has got to be the actual users created. Who wants to run a mailserver without virtual users and virtual domains in 2008 anyway?