At 10:34 03/20/2002 Wednesday, Kevin Parris wrote:
 >Send a command something like this:
 >
 >  quiet set list-name repro noack nodigest for *@*
 >
 >to set those options for all subscribers to your "list-name" list.  You
 >can use other wildcard patterns to refine the affected subscribers to
 >various subsets of the population.  The "quiet" prefix stops the server
 >from sending an email to each subscriber telling them about the changes
 >you just made.  Now, to be extremely precise, the way to change the
 >"default settings" is to use the list-header keyword by that name, since
 >anything you do by a SET command as illustrated above, actually apples to
 >the "current settings" in effect for the subscribers at the time the
 >command finishes.  The list header keyword determines what settings a
 >subscriber will be given at the time they join the list, but they are free
 >to change most of them later as they wish.

So, for completeness:

1) first update the list definitions, then

2) do the QUIET SET

Of course there are always second order effects e.g., a batch job system
like you might find in MVS (OS/390) might not "want" to get an ack or
repro since the auto- mail might be unexpected.  Or for certain
distribution options, it might "break" the receiver's successful
processing of the inbox.