Using Active Directory distribution groups in Postfix

From Zarafa wiki

Active Directory has the possibility to create distribution groups which can be used as an email distribution list. This article show you how to use the distribution group as a mailing list for Postfix.

To use integrate Postfix with distribution groups, you need Postfix 2.4 or higher.

To configure Postfix for the distribution groups, add/change the following options in the Postfix files.

main.cf

local_recipient_maps = $virtual_alias_maps

virtual_mailbox_domains = example.com
virtual_transport = zarafa:
virtual_mailbox_maps = ldap:/etc/postfix/ldap-users.cf
virtual_alias_maps = ldap:/etc/postfix/ldap-groups.cf

ldap-users.cf

server_host = ads_server_ip
search_base = dc=example,dc=local
version = 3
query_filter = (&(objectClass=person)(mail=%s))
result_attribute = mail
bind = yes
bind_dn = cn=Administrator,cn=Users,dc=example,dc=local
bind_pw = password

ldap-groups.cf

server_host = ads_server_ip
search_base = dc=example,dc=local
version = 3
query_filter = (&(objectClass=group)(mail=%s))
leaf_result_attribute = mail
special_result_attribute = member
bind = yes
bind_dn = cn=Administrator,cn=Users,dc=example,dc=local
bind_pw = password

Master.cf

zarafa  unix   -      n       n       -       -       pipe 
  flags= user=vmail argv=/usr/bin/zarafa-dagent -R ${recipient}