[Dovecot] problem with dovecot and thunderbird while deleting

[the.buratino at rambler.ru]

Hello!

I have very strange problem with dovecot and thunderbird while deleting
messages. The problem is that they are not actually deleted from storage
filesystem and if I later run mutt I can perfectly see them, though
marked with 'D', so mutt ask to delete them on exit and this time they
dissapear from filesystem. I enabled in thunderbird 'remove it
iimediately' feature, but this doesn't help. When I delete message from
mutt it removed from filesystem just fine.

IMAP server:
  OS: FreeBSD 6.1p2
  dovecot: dovecot-1.0.b9

Client:
  OS: Debian sarge
  Thunderbird: thunderbird    1.5.0.4 (from backports.org)

Any suggestions ?