Greetings.
We have a moderately sized Mailman installation (+2000 mailing lists) which recently upgraded a long-standing Mailman v2.1.5 service to v2.1.14. The upgrade went quite well, but since the upgrade the list owners of the DEFAULT_SITE_LIST (i.e. "mailman") mailing list are seeing a marked increase in the number of undeliverable emails to (other) list owner addresses, which the "mailman" list owners did not see with the previous version/installation of the software. While unlikely, they may have been a customization in either Mailman or Postfix that was lost in the transition; the logic in ~/Mailman/Message.py which sends list owner bounces to DEFAULT_SITE_LIST seems unchanged since 2.1.5 (at least).
Let me be clear: these are valid bounces from some list owner addresses that do not deliver, because a person who was a list owner has departed the organization and the mailbox to which a list owner address routes no longer exists. These messages not errors in Mailman.
Often, a single list owner address will bounce to the DEFAULT_SITE_LIST, while other valid list owners remain available for that same list -- in that case, DEFAULT_SITE_LIST members need take no action. When there's just one owner for a list and that address bounces, the list is orphaned (which is good to know), but we have other means to reclaim unused lists (periodic reregistration), and the administrative notice which bounced is frequently not something that would be posted to the list anyway (e.g. spam, erroneous out-of-office mail, spoofed sender, etc.) -- particularly if the list has fallen into disuse. It would be nice to only see the bounces when there are no other list owners (of the same list) to receive them.
Are there any Mailman configuration options which adjust the handling of bouncing list owner emails, short of customizing the Messages.py or adjusting filters on the DEFAULT_SITE_LIST policies? None leap out in Defaults.py.
Thanks for any insight.