DMARC check
Inspect a domain's DMARC policy, alignment settings, and reporting addresses.
Related tools
About DMARC
DMARC (Domain-based Message Authentication, Reporting and Conformance) tells receiving mail servers what to do when a message claiming to be from your domain fails SPF or DKIM checks. It also gives you reports on who's actually sending mail "from" you.
The p= tag controls policy: none (monitor only — no action), quarantine (send to spam), or reject (refuse delivery). Most domains start at p=none for a few weeks, watch the reports, fix any legitimate senders that fail alignment, then ratchet up to p=reject.
A DMARC record without rua= (aggregate report address) gives you no visibility into what's happening. Always set it.