I sent mail at one point to all of the users on my list which were
not bouncing mail from the demon.ac.uk site.  I pleaded with them
to tell their postmaster to fix his error message configuration, since
it was inundating my lists with hundreds of error messages each day.
I had sent a lot of mail to the postmaster there, only to have him
respond and say "something must be wrong at your end."  Wanker.
 
I know of at least one other postmaster who has also contacted him
and not gotten anything done.
 
Will