Message Policies cannot be directly applied to Active Directory groups but instead need to be applied to individual Mail Servers or Mailboxes.
An indirect method of applying Message Policies can be acheived through the Policy Assignment section of the website where the 'Group' field can be used to search for mailboxes associated with an Active Directory group and then a message policy can be assigned to the individual users.
Searching based on the 'Group' can have unexpected results however as Archive Manager stores Active Directory group membership information but only ever adds users and does not remove users. This results in an indirect relationship between the actual Active Directory group membership and what Archive Manager will report.
An example of the indirect relationship would be a user who is initially a member of the Domain Users Active Directory group. Archive Manager will store this information. If that user is moved to another group, such as the Domain Admin group and removed from the Domain Users group, Archive Manager will record this user as belonging to both groups. This is by design.
STATUS
Enhancement Request TF00594060 has been submitted to Development for consideration in a future release of Archive Manager.