It just so happens that I was on vacation :-) at the time of the duplicate mailings... I returned to 3400 !! mail files. (Luckily, they are collected to disk using GONE... and a colleague was here to increase my disk to megaspace! ;-) ) I expected 400-500 pieces of mail over the 12-day period. It turns out that only 450 or so were valid of the 3400. All duplicates occurred in the May 24-25 time period (dates taken from the Date: field). I first thought that perhaps the PSU INTERBIT problem caused it, but I also received duplicate local mail. :-( The number of duplicates were unpredictable as well: 2, 6, 11, 12, 20, etc. This is FYI... I'm not sure if local servers: Listserv (1.5o w/FIX15O1) and Mailer (2.03B) or network servers (anywhere, any level) were guilty or partially guilty. It was a nightmare!