DMARC (Domain-based Message Authentication)
A policy that tells receiving mail servers what to do when SPF or DKIM checks fail for emails from your domain.
What is DMARC (Domain-based Message Authentication)?
DMARC (Domain-based Message Authentication, Reporting, and Conformance) is the third pillar of email authentication. While SPF and DKIM verify sender identity, DMARC tells receiving servers what to do when those checks fail.
DMARC policies can be set to three levels:
- p=none: Monitor only - don't take action on failures (start here)
- p=quarantine: Send failures to spam folder
- p=reject: Block failures entirely
DMARC also enables reporting, so you can receive reports about who's sending email using your domain - helping you identify spoofing attempts.
Why It Matters
- 1Completes the authentication trinity (SPF + DKIM + DMARC)
- 2Protects your domain from being spoofed by spammers
- 3Provides visibility into email authentication failures
- 4Required by many enterprise email security systems
How to Measure
Check your DNS for a _dmarc TXT record. Use our DNS Validation tool to verify the policy is properly configured.
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