Comment 4 for bug 1859011

Each object in the bounce events is a 4-tuple like (list-name, bouncing address, bounce date, bounce message). The bounce message is a Mailman.Message.Message object, but should be and apparently is rendered as the text of the message. So yes, the third line is the bouncing addresses, and it is clearly corrupted, but I suspect that is a symptom, not a cause.

I still don't really understand what's happening. Given that the message contained a large PDF attachment, I suspect this isn't a real bounce, but rather is spam sent to the list-bounces address or possibly a list post mis-sent to the list-bounces address. The size of it may have something to do with the corruption that occurred, although I still don't understand how the duplication comes about.

What's in Mailman's bounce log from the time this happened. I'm particularly interested in any 'bounce message w/no discernable addresses' or other messages just before the "Dec 30 19:53:29 2019 (13392) <BounceRunner at 140395473885088> processing 4134 queued bounces" message.

Also are there any "VERP_PROBE_REGEXP doesn't yield the right match groups:" messages in Mailman's error log from this time.