i plan to switch from uw-imap to dovecot on a couple of medium size
systems and so i have written a conversion tool that understands mbox,
mbx, and mix formats and converts to maildir format while trying to
preserve uid info, keywords, flags, subscriptions, etc. it seems to work
for me now, but i think some feedback might be useful. so if you have
some files to convert and a desire to help, please download:
http://www.spiretech.com/~joey/uw2dovecot.pl
and give it a whirl. it is very sparsely documented right now but isn't
too complex (yet). by default it copies your INBOX, mail dir, and
.mailboxlist info into Maildir. those filenames can be overridden. i'd
suggest running with -v to watch it. it requires that the output
directory not exist before starting, so it should be relatively safe. it
doesn't lock any files being read, so an active uw tree could cause it
indigestion. it's designed to run while inbound mail and pop/imap
sessions are disabled. it uses a few perl modules, but they should be
standard with perl itself. it does do everthing in memory, so the largest
message you have will be in memory and will be duplicated at least once as
crlf pairs are replaced. also, this assumes you'll change the uid format
in dovecot.conf to %08Xu%08Xv so that it doesn't change uids for the
clients.
send feedback to me and cc the list if you feel it useful. once this is
stable, i'll get it added to the dovecot wiki.