What I'd suggest then is creating an OS template and deploying that. Trying to manually copy OVZ containers just typically ends in tragedy - best case scenario, you end up with a ton of extra work trying to find all of the little things you missed along the way just to get the thing to boot.
Another thing to keep in mind - if you want to host your own mailserver _and_ you're worried about reliability, be careful about which VPS provider you go with. It's not uncommon for providers to have large blocks of IP space blacklisted due to more abusive users, and even if you choose a host...
Honestly, the easiest route here is just using a service like AmazonSES. You can send out ~50k+ emails a month for just a few bucks.
If you'd rather host your own, postfix is pretty simple to configure. If you're wanting to handle incoming mail as well, dovecot is my choice. Requires some...
Oh, don't get me wrong, I'm not denying what's taking place with those posts. Just (not so) subtly hinting that should there be more 'normal' content present by comparison, the spammy threads would get less notice :P
Speaking as someone that's had experience on the administrative side of shared webhosting.... if you really want "good" hosting, then just get a small VPS and run a simple nginx setup. Shared hosting is absolutely _awful_ - abusive users, spammy neighbors getting everyone on RBLs, constant node...
I do like the premise of limited devices - forcing you to be economical and crafty with your available resources rather than charging in with a high-schooler's "PHP runs the internet" mentality. Just, a Pi isn't really the best option for the projects I'd have in mind (Zoneminder, X10, etc).
I've been thinking about picking up a Pie for awhile to play with.. but I have a handful of those little Lenovo bricks still floating around that would honestly be a better option for... well, anything I could think of using a Pi for <_<