I decided to try emailing the abuse contact for that IP range, abuse@m247.ro. I realize that the most authentic evidence of the attack would have to come from t

I decided to try emailing the abuse contact for that IP range, abuse@m247.ro. I realize that the most authentic evidence of the attack would have to come from the Mailman administrators, but I'm doing what I can. I got a prompt response from the abuse team telling me that they forwarded the report to the customer that's using that IP address, and to let them know if it's not resolved within 48 hours. So let's see what happens.