Hi List Subscribers, In recent months we have been seeing an increasing number of bounced deliveries from libvirt mailing lists[1] due to DMARC policies on list subscriber's mail servers. IOW, many subscribers are only receiving a subset of mails sent to the libvirt mailing lists.
We believe the root cause of many of the problems is that mailman is modifying the mail subject to add the "[libvirt]" / "[libvirt-users]" prefix, and modifying the mail body to add the footer with links to the listinfo page. These modifications invalidate the DKIM signatures on mails sent to the list by some of our subscribers. This in turn causes DMARC policy rejections by the destination SMTP servers when mailman delivers messages. The solution is to disable any feature in mailman which modifies parts of the mail validated by the DKIM signature. This means removing the subject prefix and the mail body header. Further information on this approach can be seen here: https://begriffs.com/posts/2018-09-18-dmarc-mailing-list.html QEMU has made the same change on their mailing list last year: https://lists.gnu.org/archive/html/qemu-devel/2019-09/msg00416.html If you are currently doing mail filtering / sorting based on the subject prefix, you will need to change to use the List-Id header instead. I will wait until the latter part of next week before making this change to allow people time to adapt any filters. Regards, Daniel [1] technically moderators have only been seeing bounces for messages on libvirt-users-list, but that's because we've got mailman configured to send libvir-list bounces to /dev/null. -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :| _______________________________________________ libvirt-users mailing list libvirt-users@redhat.com https://www.redhat.com/mailman/listinfo/libvirt-users
