> How about a feature that would instruct Listserv to simply swallow bounces
> containing a certain string, such as "transient failure", or containing the
> address of a particularly verbose mail server that complains a lot about
> transient delivery outages with do-nothing messages?
 
Work on email vendors to support the new Internet proposed standard for
Delivery Status Notifications.  DSNs allow LISTSERV to understand
bounce messages and act accordingly.  LISTSERV 1.8c supports them, as
does the latest version of Unix sendmail.