I post "posting guidelines" to my list automatically each week at the
same time. The guidelines have not changed for about two months.
 
Today, my posting was caught by listserv's duplicate message filter
and I received a rejection notice ("Your message is being returned to
you unprocessed because it appears to have already been distributed to
the RPLIST list...").
 
What could have happened? How come the filter was triggered this week
and never before? The only explanation I can think of is that listserv
memorizes postings for exactly a week and that this time it went out a
few minutes before the week elapsed - but it seems doubtful.
 
Nicolas