Hopefully, you have clearly enumerated the purpose/mission of
the list, and have followed up both on and/or off list, as
appropriate, for mis-postings.
 
As part of a strategy to reduce traffic, you might try the
following ploy: with sufficient notice to the subscribers, update
the list defintion headers so that list replies are defaulted
to the sender of the original message, and NOT back to the
list i.e.,
 
Reply-To= Sender,Respect
 
Also some subscribers might be satisfied if they used the DIGEST or
INDEX distribution options (assuming that your have notebook archives
or, for DIGEST, allowed THAT possibility via another list keyword
definition).
 
/Pete