DMARC Alignment Simulator

Simulate DMARC pass or fail from Header From, SPF domain, DKIM domain and alignment modes.

Need help with the calculation?
Ask AI about this article
The assistant can make mistakes. Check important calculations and decisions. By sending a message, you agree to the Terms of Use and acknowledge the Privacy Policy.

This simulator checks whether SPF or DKIM would align with the visible Header From domain under relaxed or strict DMARC alignment. It helps explain common third-party sender and return-path scenarios.

How to read the result

DMARC passes if SPF passes and aligns, or if DKIM passes and aligns. If both authenticated identifiers fail alignment, DMARC fails even when a DNS record appears valid.

Scope

The relaxed alignment check uses an approximate organizational-domain comparison. Use your mail provider or DMARC reports for final production diagnosis.