[Dovecot] questions about ldap auth

Hi all. I have a couple of questions. ANY of those will solve mi situation.

1. 'Complex' LDAP validation: I need to validate a user in the 2 step authentication / authorizacion mech.

The 'users' (with the password) are in ou=Person,o=Work

the group which contains the mail users is in cn=MailUsers,ou=Groups,o=Work

Can dovecot make such a thing? Cause im not shure if i can make this in a single ldap filter.

2. If not... 2.1) Does dovecot accept more than 1 ldap filter for authenticating? 2.2) Does dovecot accept an arbitrary program for authentication?

Well, that's all for now. Thanks! Gerardo