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