I think the list configuration holds the key to this mystery.

	Send= Service
   	Service=*.uoguelph.ca, uoguelph.ca

I am surprised that LISTSERV accepted a message with the list address as the
sender address. I know that LISTSERV will accept a message with another list
address as the sender address (subscribing one list to another was a kludge
in the days before Sub-List= support was added to LISTSERV), but I would have
thought that LISTSERV would have trapped a message with the same list address
as the sender address, just as it traps messages with self-referential headers
in the message body.

You can prevent future incidents of this nature by adding the following
statement to the list configuration:

	* Filter= Also,listname@listhost

If the list configuration already contains a Filter= statement, add the
following statement after the existing statement:

	* Filter= Also,whatever
	* Filter= listname@listhost

We have had incidents in which spammers have tried to post to lists using
sender addresses in the form [log in to unmask] Consequently, we now
add the following statement to the configuration of every new list:

	* Filter= Also,owner-listname@listhost

If your experience is a harbinger of what we can expect to see, I guess
we need to filter for both the list address and the owner- address.

	* Filter= Also,listname@listhost
	* Filter= owner-listname@listhost

What would we do all day if we did not have to keep finding new ways to
prevent 'bad guys' from exploiting our lists?

--
Paul Russell, Senior Systems Administrator
OIT Messaging Services Team
University of Notre Dame
[log in to unmask]