> What do other list owners/ LISTSERV postmasters do in handling rejection
> mail?
 
If it's for my low-volume list, I let it go for a day or two before doing
anything.  If it's for my high-volume list, I immediately set NOMAIL for
the offending address.  After setting NOMAIL, I send a message to the
subscriber (who usually doesn't get it because it also bounces) with a copy
to the postmaster at that site (who also doesn't always get it since the
problem is sometimes with the site rather than with the individual user's
address).  The list regulars know that if their mail from the list
suddenly ceases, they should send the 'query' command to check their
status.  On a list that sometimes exceeds 200 messages a day (but usually
is 80-100), there's no way I can do anything except send a prompt
NOMAIL command.
   --Natalie ([log in to unmask])