Apparently my maildir woes with imap stem from the fact that dovecot cannot handle a mix of maildir and mbox folders.[1] Next I am going to try mailutils-imap4d.
UPDATE 2005-08-30-12:14: mailutils-imap4d is no good. squirrelmail cannot get its inbox, imp3 cannot log in at all with it. I am back to dovecot for now.
[1] Dovecot FAQ http://wiki.dovecot.org/moin.cgi/QuestionsAndAnswers#head-ca096174a590558f7ad33420c3ccb62e989ac063