Hi,
A few updates on the general issues related to bouncing:
1. We worked with Mailman developers to improve the bounce parsing so it's less likely miss-process a bounce message. This might help in a few cases where list owners were getting unsubscribed. This was deployed a few hours ago. https://phabricator.wikimedia.org/T285120
2. We're looking into enabling "verp probes". If an address hits the bounce score, Mailman will send them a dedicated email, and if *that* mail bounces, then they get unsubscribed. This will prevent getting unsubscribed when spam/viruses go to the -owner address and are bounced. https://phabricator.wikimedia.org/T285361
3. We're discussing with upstream about just disabling bounce processing of the -owner address altogether. https://gitlab.com/mailman/mailman/-/issues/912
If you're still running into bouncing issues or other issues please let us know and we'll look into them.
Thanks, -- Kunal