Dovecot and Postfix on a small FreeBSD VPS. Easy to set up, and it takes almost no effort to maintain once you've got it running. (The last time I modified my Postfix configuration was over a year ago, to relax my attachment size limit.) Between the FreeBSD handbook and the official Postfix documentation, all the info one could possibly need is provided.
A combination of Postgrey and SpamAssassin keeps my inbox spam free. You can also use mutt rather than Dovecot IMAP if you prefer to read your mail on the command line. Likewise, Debian will work just as well as FreeBSD in this role, if you're more comfortable on Linux. (Debconf even gives you a menu-driven Postfix configuration builder, it doesn't get any easier.)
Backups are handled by nightly rsync cron job on a local machine. I don't really have to think about them, aside from checking once in a while to make sure they're still running.
I have to laugh at all the self-proclaimed hackers in this thread claiming that setting up a personal email server is too difficult, takes too much time – or that they have "better things to do". No, I'm not one of those who would argue that a "real hacker" always has to do things the hardest way possible, quite the opposite. But at some point you have to ask yourself: if setting up a small mail server on a *nix system – a task extremely well documented and understood, a task that yields real technical and privacy benefits, a task that the operating system itself will hold your hand through if you're using Debian or Ubuntu – is too much of a challenge for you, then in what sense can you possibly call yourself a hacker?
It's dealing with all the other issues that's an immense pain. SpamAssassin is not always a magic bullet, deliverability to third-party mail servers can be a major problem even if you follow all the rules, and Gmail's UI has a number of advantages that many mail programs can't compete with.
If you compare the hours of time a month that takes with the up-front elimination of hassle that Google Apps provides, it's not hard to see why a hacker might prefer to just outsource it and focus on tasks more pleasing to them.
Alas the technology does not seem to be quite there yet and the work required to get basically a full personally hosted webapp suite is not trivial. That said, I think in the future we will see a lot more 'appliances' that run as VMs or on low cost low power all ways on hardware. Backed by a business model something like wordpress. Meaning that there is a dot com where you can get it remotely hosted for you, and there is a dot org where you can download and host the app yourself.
Plus stuff like the personal router project http://pr.lcs.mit.edu/ would make a pretty interesting paradigm change.
[1]: http://www.globalscaletechnologies.com/p-22-sheevaplug-dev-k... [2]: https://pogoplug.com/devices
Harald's suggestions boil down to
The first suggestions might work for me, but what does everyone else use? If you host your own what software?Lastly, what do you think of a home appliance (basically a server the size of a router with a web interface) that people could install in their home to host some of their important data. Obviously it wouldn't be reliable enough for Email, but might be good enough for docs, password hosting, bookmarks, contact list, etc...