Authentification problem with cirillic password

[kilg]

I have zimbra server with external(Active Directory) authentification.
Same users in my company use russian language in them password and I can't setup them mail clients to use IMAP. I try: outlook, thunderbird, but zimbra don't authorize this users with russian password.
This is audit.log:

2010-07-01 13:04:54,026 WARN  [ImapServer-191] [ip=192.168.0.27;] security - cmd=Auth; account=user@domain.ru; protocol=imap; error=authentication failed for user, external LDAP auth failed, [LDAP: error code 49 - 80090308: LdapErr: DSID-0C0903AA, comment: AcceptSecurityContext error, data 52e, v1772

I checked, users with english password authorized very well.
This problems stay only when used mail clients, authorization in web-interface with russian password is well.
I think, problem is in IMAP authorisation(and POP3 too).
How can I do to use russian letter in users password? It's not true to deny users to use russian password.

PS: sorry for my bad english