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