← All insights · Mon, 31 Aug 2026

The email authentication funnel: 91.7% publish SPF, only 26.7% actually reject

Follow mail-enabled domains from "publishes a record" to "enforces it." Most drop out.

We took every mail-enabled domain in the sample (those with MX) and walked them down the authentication funnel:

Mail-enabled (have MX), 100%
Publish SPF, 91.7%
Publish DMARC, 77.6%
Enforce (quarantine or reject), 48.9%
Reject (p=reject), 26.7%

The story is the drop-off. Publishing SPF is nearly universal (91.7%) and DMARC adoption is high (77.6%), but only 48.9% enforce anything (quarantine or reject), and just 26.7% reach p=reject. Every step down that funnel is a domain that did the paperwork but left the door open. If you operate a domain, the win isn't publishing another record, it's moving one step down the funnel toward enforcement.

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Verify a real address → This is aggregate DNS data. To check whether a specific email address exists and is deliverable, use MailTester Ninja , real-time, nothing stored.

Data: MailTester Ninja Email Infrastructure Index, 50,000 domains, snapshot Mon, 31 Aug 2026 04:18:17 GMT. Reuse freely under CC BY 4.0.

FAQ

What share of domains enforce DMARC with p=reject?

Among mail-enabled domains in this 50,000-domain sample, 26.7% enforce DMARC with p=reject and 48.9% enforce at least quarantine.

Data · Email checker · Email verifier · Blocklist checker · Blocklists explained · Widget

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