[Dovecot] problem with some mailboxes (failed: Is a directory)

[mikie at x.org.pl]

>> Jan 29 16:24:28 mailserv dovecot: IMAP(username):
>> unlink(/var/spool/mail/imap/user/username/Maildir/cur/Sent:2,ST)
>> failed:
>> Is a directory
> Something has created a directory called Sent inside Maldir/cur or
> Maildir/new. Dovecot treats it as a message and so it has added \Seen
> and \Deleted flags to it. Dovecot didn't create the Sent directory,
> look at other software/scripts you have.

Indeed.

>> There is one workaround I know which is:
>> rm /var/spool/mail/imap/user/username/Maildir/dovecot.index*
> Delete the Sent* directory.

Seems like there used to be any software or exadmin which created those
directories. I can not find out the source of it. I'm thinking about
deleting all those but I am wondering if Maildir specification does allow
any subdirectories in new/cur/tmp?

Thanks a lot!