Thanks to everyone for their suggestions.

The wildcard approach wouldn't work in this case, because the listserv
kept choking on the two asterisks in the bad address. The quotation mark
approach (delete <listname> "x@@y.z") probably would have worked if I had
done it correctly, but I think I screwed it up by typing in both the email
address and the subscriber's name.

In any case, Trish spent hours helping me out with it. We decided to edit
the list directly, which got even more complicated since we use Listserv
1.7b on a VM machine. The final outcome was to replace the dang thing with
a backup copy--fortunately, there were not many new subscriptions
yesterday, so I don't have much catch-up to do.

Thanks again!

Ione

-- Ione L. Smith, DVM -- Department of Comparative Medicine --
-- University of Tennessee,  College of Veterinary Medicine --
      ==================================================
       http://funnelweb.utcc.utk.edu/~ilsmith/SVME.html
          The Society for Veterinary Medical Ethics
      http://funnelweb.utcc.utk.edu/~ilsmith/ethics.html
          for all sides of the AR/AW/anti-AR debate
      http://funnelweb.utcc.utk.edu/~ilsmith/stereo.html
            the stereotypical behaviors database
      ==================================================
        I am always willing to learn, however I do not
        always like to be taught. -- Winston Churchill