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