[Dovecot] Public folders and groups

[b m]

Currently I have dovecot working with Active Directory authentication and 
public folders with acl. In acl I have the users I want to access the public 
folders. It'll be easier for me to use one group instead of 50 users but I 
can't get it to work. From where does dovecot get the "group" attribute for a 
user? Can it read the groups that a user belongs from AD?