Started looking at E-mail.

Installed exim4. Specified server type as 'handling incoming mail, outgoing mail by smarthost.'.

Setup virtual domains by following instructions at: http://www.debuntu.org/2006/05/17/52-how-to-exim4-virtual-host-on-debian-etch.

I think things work, but it's getting hard to test without having the server in its final extranet configuration.

Will later work on reading the exim virtual domains from the MySQL database.