I think that's a good idea. I know I'll be looking for some examples in a couple of months when I have enough time to dedicate setting one up properly.
You may or may not have seen it already, but in case you haven't, I'll link here the "How to NSA-proof your email" howto [1] someone just posted in the "Gmail was down" thread. Regardless of how you feel about the Black Chamber, it's an excellently well-written document on setting up your own mail-serving VPS using postfix and dovecot; the filesystem-level encryption stuff is trivially severable, and constitutes about 80% of what I'd have written (but not as well) had I not found this first. The other 20% would be setting up Baïkal for CalDAV/CardDAV service, but that's pretty straightforward and well described in the Baïkal Github repo.
(Minor quibbles about the HOWTO: I'm not sure Solr is really necessary; Dovecot seems to give me full-text search for free via IMAP. Also, I tried Z-push and it worked, but didn't support message flags, which I require, and I got tired of push pretty fast anyway. It works, and might've added message flags in the years since I tried it, but it's by no means required. Still, an excellent document, which I unreservedly recommend.)
