I wrote:
I haven't edited my .procmailrc or any of its includes for at least a
week. Yet Saturday night (27 hours after I left this office Friday)
procmail started sending me a duplicate (from foo(_at_)bar) of every incoming
message on a particular mailing list. Worse yet, the log for one of those
messages says that the recipe for that list is an "invalid regexp"
Impossible, I say--the message is a duplicate of one that was successfully
routed to the list folder!
Update: Never mind. I still haven't a clue what was going on, but it stopped
mid-afternoon on Sunday (17 hours before I came in this morning)!