550-5.7.1 Unauthenticated email from verizon.net is not accepted due to domain's DMARC policy


I’m trying to help an EMWD mailman customer with a delivery issue that occurred today with a verizon.net sender to a EMWD mailman list with all the gmail members of the list getting bounced back with the following:

host alt1.gmail-smtp-in.l.google.com []
SMTP error from remote mail server after end of data:
550-5.7.1 Unauthenticated email from verizon.net is not accepted due to domain’s
550-5.7.1 DMARC policy. Please contact the administrator of verizon.net domain
550-5.7.1 if this was a legitimate mail. Please visit
550-5.7.1 https://support.google.com/mail/answer/2451690 to learn about the
550 5.7.1 DMARC initiative. 73si21094822iou.65 - gsmtp

Is this due to the sending service actually being EMWD, not matching the expected verizon.net service?

Brian W.

Hi Brian,

It is possible that the mailing list is not configured to mitigate DMARC senders properly. What is the list domain?

Hi, and thanks.

That’s probably the issue, though I am new to DMARC.

The domain is list.studiogallerydc.com and the most relevant TXT record in DNS is:
v=spf1 include:_spf.google.com ~all

Which doesn’t define a DMARC policy. I reckon I should update this?

I was referring to a list setting that mitigates DMARC issues. The KB article for this is located at:


Both of their lists were not properly set for DMARC mitigation so I have fixed that. I believe that will improve their mail delivery.

Thanks for doing that!