[Dovecot] mbox with sub-folders and messages?

[Richard Lefebvre]

Hi,

Is it possible to have dovecot configured to use mbox format and yet
have folders that contains sub-folders and messages? I'm thinking of
a simple setup where any files directory with extension .sbd are
presented to the IMAP client without the extension. So if you have a
mbox file named BOX01 and a directory name BOX01.sdb would show has one
on the client side (note: that is the way Thunderbird keeps it's mail
locally).

I know that the Maildir format does the sub-folders+messages, but I'm
not really interested by the one file per email.

Richard