Hugh,
 
    The  difference  is  whether  mail  from that  list  is  sent  via
DISTRIBUTE or not.  If it is, then  there will be only one To: address
per mail  file, and  the mail will  come from  LISTSERV@<some LISTSERV
close to CUA>.  If it isn't, then  there will be up to 5 addresses per
file, and  the mail  will come  from LISTSERV@<peer  you're susbcribed
to>.
 
Ross Patterson
Rutgers University