I just tried to delete a top level ([EMAIL PROTECTED]) from both cyradmin and php imap_deletemailbox. The delete works, but subfolders for that user are not deleted. If however I create a user in defaultdomain (user.username) than whenever I delete the user everything is gone under him as well. I believe it is the behaviour of 2.1.1x as well.
Ken, are the subfolders left on purpose, or its and error?