I'm certainly no expert on using mutt, but it does have mail filtering capabilities. See "folder-hook" for more info.
As far as creating subdirectories, etc., mutt will store mail pretty much anywhere you want it to. So, under your ~/Mail directory, you could create a "debian" directory, and then have debian-user, debian-mentor, etc. as mail files. AFAIK, you can't have something like a mail file "debian" with subdirectories on it. Though, the difference should hardly be an issue. In my few days of using it, I have found that mutt definetely "sucks less" than many other mail clients. -- Eric G. Miller Powered by the POTATO (http://www.debian.org)!