DMARC Policy Simulator
See exactly what a receiver does with any sender — before you move from p=none to enforcement.
Runs entirely in your browser. This is the exact logic a receiving mail server uses — evaluated on your device with no account, no upload, and nothing stored. The share link carries your inputs in the URL, not on a server. How DMARC decides ↓
The simulator shows what would happen. Want to know when you're actually ready — from your real senders? Watch your domain free, and Amino tells you the moment it's safe to enforce.
Monitor your domain for free →DMARC simulator FAQ
What is a DMARC simulator?
It reproduces exactly how a receiving mail server evaluates DMARC for a message: it checks whether DKIM or SPF passed and aligned with your From: domain, then applies your policy (p, or sp/np for subdomains) to decide whether the message is delivered, sent to spam, or rejected. You enter a policy and a sender scenario and see the result and the reasoning — before you publish anything.
Why simulate before tightening my DMARC policy?
Moving from p=none to quarantine or reject is the step people hesitate on: if a legitimate sender isn't covered by your SPF or aligned DKIM, its mail starts going to spam or bouncing the moment you flip the policy. Simulating each of your senders first shows which ones would break, so you can fix them before you enforce instead of hearing it from angry recipients.
How does DMARC decide pass or fail?
DMARC passes when at least one of DKIM or SPF both passes and aligns with the From: domain. DKIM alignment compares the signing domain (d=) to the From: domain; SPF alignment compares the envelope-from (return-path) to the From: domain. Relaxed alignment (the default) matches at the organizational-domain level (so mail.example.com aligns with example.com); strict requires an exact match. If neither mechanism passes-and-aligns, DMARC fails and your policy applies.
What do sp, np and pct do?
sp sets a separate policy for subdomains of your domain; np (from DMARCbis) sets a policy specifically for non-existent subdomains, a common spoofing vector; pct tells receivers to apply your policy to only a percentage of failing mail (a legacy ramp control that DMARCbis deprecates). The simulator shows which of the three applies to a given sender and what the leftover percentage is treated as.
Why did a forwarded message or mailing list still get delivered?
Forwarding usually breaks SPF (the forwarder isn't in your SPF record) and mailing lists often modify the message so DKIM breaks too — so DMARC fails. Many receivers recognize these cases and apply a local override, delivering anyway. Behavior varies by receiver, so the simulator shows it as an override you shouldn't rely on. This is exactly why you validate with your real reports, not assumptions.
Is anything sent to a server?
No. The whole simulation runs in your browser with deterministic logic — no account, no upload, nothing stored. The Copy share link button encodes your inputs in the URL itself, so a colleague opens the exact same scenario without anything touching a server. To move from one-off what-ifs to your actual senders, free domain monitoring ingests your DMARC reports and tells you when you're ready to enforce.