[Dovecot] Both mbox and Maildir

Hi,

I would like to know if it's possible to configure dovecot so that it use mbox file format for the INBOX mailbox but Maildir format for all the subfolders.

My problem is I would like an IMAP server which allow to easily create folders and subfolders of folders, but at the same time I don't want to break all MUA which rely on /var/mail/johndoe in mbox format.

Thanks in advance.

Yann