Hm, one reason I like mbox format is that I can burn it to CD and read it with software 20 years later without a problem. Maildir is what (ex)mh uses, right? Where a mailbox is a dir and messages are files? Sort of like seeing your mailbox explode. :-)

That would be fine with something like rfs, which is optimized for small files, but I think it would kill ext2 if you have huge mailboxes (which I do — several over 1000 messages).

I guess for archival, if I had some SQL thing, I could have a script that spit everything out in mbox or something..

My archived mail is currently 507Mb (wow!), in 47450 files (with a couple of control files in each folder, I have slightly fewer actual messages). In practice, I don’t have any trouble with using MH format; EXMH as a GUI hides that detail, and the MH/NMH command line tools are very easy to use (they were designed that way, after all).

Maildir format is a little weird; the filenames are long and somewhat unintelligible, so using standard command line tools is more challenging. I’ve eneded up with a few perl/python scripts to make life easier.

Mutt speaks maildir format directly, as does courier IMAP; between the two, it’s easy to manipulate my mailboxes. Also (as you mentioned) I keep my primary mail on my laptop in MH format; the maildir stuff is a) for other cfrq.net users that use IMAP and/or webmail, and b) for when I’m travelling and using webmail instead of my laptop.