Many thanks to those who helped me figure out the problem at gu.edu.edu.
 
For future reference of those who have not yet experienced this particular
problem (I still don't know why I got two of each error, and it isn't
because of the ERRORS-TO definition) I append part of the message from the
postmaster at the site involved. I understand what she says, but fail to
see the rationale behind such an arrangement.  Sounds like a lot of
unnecessary maintenance to me.  Why don't they just send the mail out with
the login addresses?
 
Again, thanks, and I have restored service to the problem causer, who
sent me a contrite message.
 
        Douglas Winship    Austin, Texas    [log in to unmask]
                    Secondary AUTOCAT Listowner
 
From: Narelle Stone <[log in to unmask]>    (the postmaster)
 
                  text deleted
 
        We alias all outgoing mail addresses to:
[log in to unmask] All incoming mail goes to our mailserver
(griffin)  to be rewritten to the form [log in to unmask]
 
                    text deleted
 
)So, in your sub list, look at the "division" of your subscriber and the
)surname.  If the surname is Bilge and the division is swi, the login
)may be swibilge .  Hope you have a great year, with no errors!  dw