Me, when I start explaining DMARC, DKIM and how they work with mailing lists.
@monsieuricon Has no one suggested they just make a rule to never classify mailing list emails as spam?
I'm not sure why they even use gmail, even though I do I use a forwarder email for mailing lists, the issue (which you're probably aware of) being that majordomo sends mail in batch to many recipients on the same domain and every once in a while one of them breaches daily limits and cause delivery delays for everyone else...