A number of users on a list had an issue with mail; Mailman messages were being rejected with a 550 error due to a problem with their server.
For some reason, these bounce messages were then appearing on the list. They were then sent out again, going out to the faulty address, and bouncing again, which returned to the list, and so on.
What setting could cause this? I haven't encountered a situation where bounces ended up being resent to the list, instead of going to the list owner. The bounce settings for this list are below:
bounce_processing = 1 bounce_score_threshold = 3.0 bounce_info_stale_after = 7 bounce_you_are_disabled_warnings = 3 bounce_you_are_disabled_warnings_interval = 7 bounce_unrecognized_goes_to_list_owner = True bounce_notify_owner_on_disable = True bounce_notify_owner_on_removal = True