>>If that doesn't do it, and if your are a LISTSERV maintainer, or acquire
 >her help,
 >>do a DISTRIBUTE MAIL  to all subscribers and see if the mail returns a
 >message.
 >
 >Will that tell me specifically what address is the problem?

On the same basis as your doing a "binary search" but in one-sixth of your time ...
 >
 >By twice splitting the subscriber list in half and then e-mailing a unique
 >message to each
 >half, I've narrowed it down to 195 addresses.  I figure 5 more cuts and
 >I'll have it narrowed
 >down to 3 addresses.

/Pete Weiss