make unsubscribe possible for anyone for all lists
Now, a list admin can set a list so that others cannot unsubscribe(under Admin → Edit List Config → Privileges → Who can unsubscribe (unsubscribe) ). Can we lock this so that anyone may unsubscribe? (maybe we don’t want to lock it, and we want to allow list admins to decide if they are notified or not when somebody unsubscribes.)
(from redmine: created on 2010-03-08, closed on 2010-03-27, relates #2073 (closed))