DMARC

lastmod 2025-03-26created 2025-03-261 edits

DMARC (Domain-based Message Authentication, Reporting and Conformance) is an email authentication protocol. It is designed to let email domain owners protect their domains from unauthorized use, known as email spoofing. The purpose of implementing DMARC is to protect domains from being used in cyber threats such as business email compromise, phishing emails, and email fraud.

Once a DMARC DNS record is published, receiving email servers check incoming email against the policy published by the domain owner. If an email passes authentication, it is delivered and can be trusted. If an email fails the check, it can be delivered, quarantined, or rejected according to the instructions in the DMARC record.

DMARC extends two existing mechanisms, Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM). A domain's administrator can publish a policy in a DNS record to specify which mechanism (DKIM, SPF, or both) is used when sending email from that domain. It specifies how to check the From: field shown to end users, how receivers should handle failures, and how daily reports are delivered.

DMARC is defined in RFC 7489, dated March 12, 2015, with "Informational" status.

See also

• SMTP
• Email
• SPF
• DKIM
• DMARC

Favorite site

• DMARC - Wikipedia
• Spammers are making better use of SPF, DKIM, and DMARC | GeekNews
• Understanding SPF, DKIM, and DMARC: A Simple Guide | GeekNews
  • [Original] Github - nicanorflavier/spf-dkim-dmarc-simplified - Understanding SPF, DKIM, and DMARC: A Simple Guide
• See interactively how email SPF/DKIM/DMARC works | GeekNews
  • [Original] Learn and Test DMARC