Subscribe/unsubscribe is operated to $primary_*_map. For example, subscription of remote administrators is operated into both $primary_admin_member_map and $primary_admin_recipient_map. Unsubscription of remote administrators is operated into both $primary_admin_member_map and $primary_admin_recipient_map. Why use primary_*_map ? If we use admin_member_maps and admin_recipient_maps, it causes a problem. Subscription should be operated into one map. So we should operate it into primary_*_map. Unsubscription must be same since xxx_maps is composed of different privileged maps. For example, $member_maps is as follows. It contais a list of member and a list of remote administrators. member_maps = $primary_member_map $admin_member_maps So unsubscription operated for $member_maps may cause unsubscription of remote administrators. It is wrong logic.