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]