[Mailman-Users] Recent trouble with DMARC Munging

[Scott Neader]

I'm using Mailman version 2.1.23.  Since late 2014, I've been successfully
using the "Munge From" option under Privacy Options > Sender filters >
"Action to take when anyone posts to the list from a domain with a DMARC
Reject/Quarantine Policy."  Mail from users using AOL, Yahoo and others
with a DMARC policy of quarantine or reject had the FROM field munged:

FROM: John Doe <someuser at yahoo.com>

becomes

FROM: John Doe via Listname <listname at ourdomain.com>

Again, this has been working GREAT for over two years.  Now, mysteriously,
this has stopped working. When yahoo.com or AOL.com users post to our
lists, the Munging is not working.  When I query for a DMARC record from
the mail server, it can see the record, so I think it's not a resolver
issue.

I'm really stumped... any pointers/ideas on where to look would be greatly
appreciated!

- Scott