[Dovecot] LDAP expired password

hi all, I'm using postfix, LDAP, dovecot and horde for webmail. user and password information is stored in LDAP. I'm attempting to get password aging working properly and am not having much luck. even if password has expired user can login, can i tell dovecot to control the LDAP field shadowexpired? or is there some other way to check properly that the password is expired before allowing the user log in?

thank's /roby