Why is it virtually every message now in my Spam folder has this warning: “This email has failed its domain authentication requirements. It may be spoofed or improperly forwarded. Mark as legitimate.”? This is something new. What does it mean? Why is every message marked? Can they all “fail?” Is there an option to turn off this warning?
I expect this means the email failed a DMARC check. DMARC is part of a system to prevent people sending emails pretending to be other people, or at least ensuring such "spoofed" messages end up in the spam folder.
If you're seeing that warning on a legitimate email, the sender has something wrongly configured. Because it's the sender who publishes the instruction to email software saying, effectively, "If you receive an email that says it's from me, but it doesn't meet these requirements, consider it spam." The email app is just complying with that.
Interestingly, the DMARC record at usps.com specifies p=reject which I thought meant that spoofed messages should be blocked from delivery, compared to p=quarantine which means "put this in the spam folder". But I'm no expert.
Thanks for your reply MEDWDS. Still a mystery apparently.
Understanding "domain authentication failed" email warning
