Another thing you might evaluate is the use of
 
REPLY-TO: SENDER,RESPECT
 
This is highly list-traffic/user-knowledge dependent.
One of the lists that I co-administer did switch to
this when alot of replies that should have gone to
the sender were in fact being distributed to the
2.5 k users.  With the continual subscriber churn,
it was not possible to sufficiently educate the
subscribers to reply-to properly.
 
Now the on-list responses seem better focused.
 
Pete Weiss at Penn State