> I am at my wits end trying to troubleshoot a user that says a message
 > they send to the list two days ago went out again all by itself.
 > Can anyone point me in the right direction, or tell me what might
 > cause this.

First make sure it really did get distributed twice; many non-technical
users are easily confused on this score.  Checking the notebooks is
a good way to tell.

Duplicates are often caused by mailers mishandling messages; dropping
the envelope and using the header "To:" address (which points to the
list) is a fairly common sysadmin error when implementing virus or
spam checking.  If the list is not set to confirm postings, any such
loop results in the possibility of a duplicate posting.  Much depends
on the list volume and the amount of time involved between first send
and the looped copy bouncing back; this is because of the number of
previous messages "remembered" by LISTSERV for dupe checking.

See if you can get full headers of both copies.  You may be able to
see which host is causing the loop.

Alternatively, it used to be fairly common for mailers to lose an SMTP
connection after the receiving host had saved the message, and before
it sent the "message accepted" indication.  This caused the mailer
on the sending host to try again, resulting in dupes.  Though this
doesn't seem as common as it used to be, it's still possible.

Dennis Boone
H-Net