Perhaps you have noticed that 'mailman' implements an option to get around the fundamentally broken concept of DMARC, and that the 44net mailing list has that functionality turned on. (This is the "DMARC-Munge-From" option).
It is dependent on the DMARC-implementing site declaring so publicly by publishing a TXT record in its DNS entries. Sites which implement DMARC without the corrective DNS entry are making an already-broken protocol behave even more poorly.
One recommended procedure is to set a mailman option which refuses postings from email providers that implement DMARC and informs the subscriber attempting to post to the list that their email provider is running a non-standards-compliant email system, that their mail is being refused as being unforwardable, and that they should find some other email provider instead. I have considered turning this option on but, while esthetically pleasing, it would reduce the functionality of the list, and so I have not. That doesn't mean that DMARC isn't a badly broken misconception; it is. It should NOT BE USED. - Brian
On Sat, Nov 10, 2018 at 06:31:49AM -0600, Neil Johnson wrote:
Unfortunately this breaks mailing list software like mailman (used for this list) which tries to make e-mail from the list appear as if it is coming from the original sender.
The changes that are required to fix the issue change the functionality of the list software in ways users may not like.