Why? Well, in my case, I want something better than 20k files in one nnmh directory.<p>On my test Maildir (copy of my INBOX from a few weeks ago), `du -s ~/Maildir` reported 81MB and the CouchDb database is 76.3MB.<p>There's lots to be done:<p>* handle MIME as binary objects where possible. That should use less storage space than the uuencoded message parts.<p>* store seen and other Maildir flags<p>* write (non-web) frontends, preferably gnus.