What is DMARC?
Tells inboxes what to do with mail that fails SPF or DKIM, and where to send reports.
Written by the SkyQon engineering team · Last verified 4 August 2026
Why it matters
SPF and DKIM produce a result. DMARC is what turns that result into an instruction — accept, quarantine or reject — and it is the only one of the three that sends you reports about mail claiming to come from your domain.
The standard
RFC 7489 (2015). A DNS TXT record at _dmarc.<domain> carrying a policy (p=none, p=quarantine or p=reject), an alignment mode, an optional rollout percentage, and report destinations (rua, ruf).
Official text: RFC 7489
How it fails
By far the most common failure is staying at p=none forever. p=none authorises nothing and blocks nothing; it only collects reports. To an attacker, a domain that has sat at p=none for years is indistinguishable from a domain with no DMARC at all. The second failure is publishing an rua address and never reading what arrives at it.
Related terms
Check this on your own domain
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