LISTSERV throws away source routes while processing incoming messages.
Most of the time the problem is that the user sends the command via TELL
and replied by mail, and the local mail system forces Internet addresses
on all replies but the equivalence is not in BITEARN NODES. But I have
indeed seen a number of more exotic cases. The good thing is that it
makes it clear to users whose hostname depends on how far from the
terminal room entrance they sat on that particular day that there is
something wrong with their system :-)
Eric