[Dovecot] Problem with allow_nets passdb parameter and Postfix

[Неворотин Вадим]

I use Dovecot for SASL authentication from Postfix. In Postfix main.cf I
have:

smtpd_sasl_type = dovecot

It works good, but now I need to allow users to connect by IMAP only from
given IP adresses. I've added extra field allow_nets to passdb in Dovecot,
and IMAP authentication works fine. But now I can't connect to my SMTP
server because when smtpd ask dovecot about user authentification, dovecot
always denied it. Even if I try to connect to SMTP from correct IP, listed
in allow_nets for user. In dovecot log I have messages about incorrect ip
like this:

dovecot: 2010-02-15 13:28:51 Info: auth(default): passwd-file(malamut):
lookup: user=malamut file=/etc/dovecot/temp.users
dovecot: 2010-02-15 13:28:51 Info: auth(default): passdb(malamut):
allow_nets check failed: Remote IP not known
dovecot: 2010-02-15 13:28:53 Info: auth(default): client out: FAIL 7
user=malamut

Problem is clear: smtpd don't send client IP to dovecot authentication
socket. But I need to limit the ability of connection to users only from
specific IP. Both for SMTP and IMAP. How can I do that? I use dovecot 1.0.15
and Postfix 2.5.5 on Debian Lenny.