[Dovecot] Reiserfs

If you don't got to Reiser then you might as well stay with what you got. Reiser is the only file system that's fast when it comes to lots of fules in a single directory. That's it's strongest point.

But conversion isn't trivial but not too dificult. You just copy off all your files onto another drive. Reformat with reiser, the copy them all back.

Reiser is different because it's a file system on top of a database. That's what makes it so fast on maildir specifically. It's the best where you have a lot of small files.