[dovecot] Folders with mail and subfolders

I have a maildir hierarchy (built originally with Courier-IMAP) where some folders contain both email and subfolders. Using Dovecot I cannot see the mail in the top folders: I can only see the subfolders.

Is this an RFC restriction or a Dovecot restriction? If the latter, is it planned to change?

Otherwise: just started using Dovecot, and I'm very impressed with the speed of it. Thanks!

Keith