DMARC (Domain-based Message Authentication, Reporting and Conformance) is a control system and tells the receiving mail server whether to accept an e-mail message if SPF and/or DKIM failed.

To specify how the receiving mail server should handle failed (SPF and/or DKIM) checks, we can set the following parameters.

  • p=none (let the receiving mail server decide)
  • p=quarantine (set the e-mail as SPAM)
  • p=reject (do NOT deliver the e-mail to the receiver)

To setup DMARC you have to create a subdomain with the following format

TXT record

v=DMARC1; p=reject;;

With the rua= parameter the receiving mail server can notify the domain owner about abuse and problems.

Check your DMARC txt record