I  have received  50% of  YES and  50%  of NO,  roughly. But  I did  receive
interesting comments. I am now ready to propose the following solution (Jacob,
please tell me if it would solve your problem or not):
 
  After giving a little thought to the problem, I came out with the conclusion
that the  header-cleanup job LISTSERV does  is very good for  human beings who
want a CLEAR header which they will be able to understand at first glance, but
very bad for a  program who wants to gather as much info  as possible from the
header. The program  does not care if the  header is 30 lines long  and is not
formatted in two columns, with adresses  folded across userids, etc. The human
reader does not care about the message-id, Received: tags, etc.
 
  I therefore  suggest the following  implementation: each subscriber  can, by
means of  the SET command  (and therefore on a  list per list  basis), request
LISTSERV to send it either cleansed headers  (as it does at present -- default
option) or a FULL header which includes ALL the crappy 'Received:' tags. There
are now two possibilities:
 
1) The full header includes all the  original tags, with the ones generated by
   LISTSERV overriding the ones from the original mailfile. In other words, it
   would work like now with NO tag being removed or commented out.
 
2)  The  full  header  includes  all  the  original  tags  untouched,  with  a
   'Received:' tag being added on top of the mailfile by LISTSERV.
 
3) Same as item 2, except that the new tags generated by LISTSERV are added in
   the form of 'X-LSVTAG:' (eg 'X-LSVTAG: Sender: nianaia <XXX@FRECP11>')
 
Comments will be much appreciated.
 
  Eric