> Terry, I wrote the code which generates this message because LSTSRV-L got
> something like  150 copies of the  same posting from someone  at BROWNVM.
> It's a  network problem,  somewhere an  RSCS is  resending the  same file
> zillions of time for some reason.
>
>   Eric
 
As always, Eric's answer is correct.  However, some of you or your
subscribers may need a little more explanation of what is happening
and what the implications are.
 
What you are seeing is the 'cure' for a maze of 'duplicate posting'
problems.  The situation:  LISTSERV for whatever reason gets
multiple copies of a message.  This is what happened BEFORE Eric
wrote the 'duplicate posting' logic.
 
1).  User would send one message to the list.
 
2).  Somewhere, that message gets duplicated.  It may be before
LISTSERV posted it, or afterward but that's not important.
 
3).  LISTSERV posted each and every copy to every person on the
list.  Of course, if the duplicate was created by a systematic
gateway problem, the duplicates were duplicated, etc. until
something broke, filled up, or someone noticed and intervened.
This distribution was LISTSERV's duty and it did it well.
 
Now, if I've understood Eric's postings and the notes on LISTSERV
upgrades, this is what happens (Eric, please correct me where I'm
wrong).
 
1).  User sends one message.
 
2).  Somewhere the message is duplicated.
 
3).  LISTSERV distributes the first one (of course it doesn't know
it's the first of several) and uses some logic to generate a
specific unique checksum (or signature) of Eric's design.  Every
incoming message for an assigned period of time is checked against
this signature.  If a duplicate is found, a message is sent back to
the SENDER, JUST IN CASE ERIC's LOGIC MADE A MISTAKE OR THE USER
REALLY, REALLY, REALLY meant to send a duplicate.
 
The point of all this is that by the time you get the 'duplicate
posting' error message, THE ORIGINAL MESSAGE is ALREADY POSTED.
LISTSERV has done some more magic, and the world is made safer for
electronic mail.  :-)
 
The other main point is that the minor inconvenience to the sender
is nothing compared to the old problem of duplicate postings.  I've
been on large lists with much traffic where the duplicate traffic is
about one third the total volume.  People tend to blame LISTSERV,
but actually, LISTSERV is doing everything it can to solve the
problems which are created by the simple, old, idea that's coded
into most mailer's distribution logic.  The old idea?  Two copies
are better than none.  And I still agree with that logic.  But when
two become four become eight, etc. it's another matter.
 
THANK's AGAIN ERIC, for doing your part to make up for the rest of
the world's problems!!!!!!!!!
 
Joe Moore
South Dakota State University