I've gotten "undelivered for x days" for items as close to year old as
to make no difference.  The only good thing about them is, usually, you
don't get many of them (they don't continue to come for every single
message of the past x days).  If you do continue to get these, by all
means complain to the postmaster at the relevant site and continue to
do so until the error messages stop.
 
        Douglas Winship    Austin, Texas    [log in to unmask]
                    Secondary AUTOCAT Listowner
                              MEDLAB-L