Aidan,
Duplicate postings from ARPA lists are quite common. It is due to
a problem with some (actually, many) SMTP mailers, when sending to
distribution lists. LISTSERV attempts to clean up each piece of mail
that it sends, so you don't see all of the Received: lines, that would
indicate where the problem really lies. Specifically, the problem is
that the sending SMTP process iterates over the list of recipients
(from the distribution list), dutifully send copies of the posting.
At some point, it fails to make a connection to the receiving SMTP
process (the host is down, or the gateway to the host's network is
down, etc.) The sending SMTP then requeues the posting for delivery at
a later time. If you are earlier on the list that the problem
address, you'll get a copy the first time, and then again when it's
resent. If you are later that the problem, you'll get a copy after
the problem address has be passed. Many SMTP systems will try to send
mail repeatedly for up to three days before aborting entirely, so if
you're an early address, you may see *many* copies.
A good SMTP would only resend to problem addresses, and skip over
them during the first pass. But then, we all know bad programmers,
right?
Ross Patterson
Rutgers University
Center for Computer and Information Systems
ATT et al : (201) 932-3435
BITNET : A024012@RUTVM1
ARPANet : A024012%RUTVM1.BITNET@WISCVM
Snail Mail : PO Box 879, Piscataway, NJ 08855-0879
|