We got a bunch of bounces, those users were unsubscribed (on the order of like 7k!) and then for each one, mailman3 sends an email to the list owner saying the address was unsubscribed and then to the address itself, which probably results in another bounce. There's also some issue when a list owner is bouncing.
The outgoing queue is also processing very slowly, I think there's another bad/unoptimized query here, it's sending 1 email every 5 seconds...at this rate it'll take 70 hours to empty the queue.
We should just delete all the "You have been unsubscribed" emails out of the queue. I don't know if those can just be deleted off of disk or if they need to be removed from the database too. maybe there's a REST API method for it.