[tobbyb]

we have a pretty easy to use multi-domain mail server in a Debian Wheezy container [1] based on LXC. It's an integrated package with Postfix, Dovecot, a GUI admin (Vimbadmin) and Roundcube webmail preconfigured so you can start with a GUI admin right away and add domains and users. It's like a small head start and works out of the box and there is a comprehensive guide on how to use it and configuring a mail server including a screencast [2], that could be worth exploring.

But the thing with a mail server is there are number of steps beyond installation. You need to configure SSL and spam filtering, then your DNS and SPF records. Then you need to test and ensure your mail is making it through. And a mail server requires constant attention. It's not a configure once and forget. You need to take care of spam filtering, anti virus, and ensuring your mail server is up pretty much 24/7 without break, as email is important and cannot be down. This can become a huge time sink, hence folks leaning towards hosted solutions like Gmail etc which take care of all of that for a small cost.

[1] https://www.flockport.com/apps/mailbox/

[2] https://www.flockport.com/using-the-flockport-mailserver/