Help needed with a DMARC issue related to Mailgun

Hi! So, a colleague subscribes to a mailing list that I believe is “operated” by Mailgun. At least Mailgun appears in the DMARC report as having an issue with a DKIM failure. I used the dmarcian “DMARC XML-to-Human Converter” to produce a nice looking report. Would it be appropriate to post a link to the report here?

Anyway, what I think is happening is Mailgun might be changing a header such that the DKIM check fails. Our current DMARC policy is “reject” so messages sent by my colleague aren’t being sent to the list. Ideally, I would like to find a solution that doesn’t require me to change our DMARC policy or our strict SPF policy (“-all” for non-authorized servers). Even though Mailgun is identified as a server having an issue, I see “” in the report as well. So, I’m a bit confused as to what is at work.

I’ve done research at the Mailgun site and everything I read is related to us having a Mailgun account and setting up a DKIM record for Mailgun. Would a solution be to subscribe to Mailgun, generate an appropriate DKIM record and add it to our DNS zone for our domain?

The flow is this: my colleague sends email, from her custom domain, to the mailing list email address. The message she sends is accepted by the mail server hosting the mailing list but her message doesn’t get sent to the mailing list subscribers. Then, I get the DMARC report which reports the DKIM failure. We are not Mailgun or customers or subscribers.

Thanks in advance!

This is not a problem that you can fix. The mailing list operator needs to make their mailing list DMARC compatible.

Thanks for the information! I’ll see if I can get to provide some assistance regarding DMARC compatibility. Otherwise, I’ll have to figure out plan ‘B’.

Thanks again!

1 Like