How does one exclude a host from having its address modified with a
  .bitnet?   An internal host (mailserver) does NOT show my newly
  build solaris-listerv box its fully qualified domain name. This will
  not change per infosec folks.  so listserv gets a post from usr1@mail1,
  not [log in to unmask] , and merrily tacks on a .BITNET.  How do I
  prevent this behavior for this one internal mail-host?