← All insights · Thu, 02 Jul 2026

The email authentication funnel: 91.5% publish SPF, only 26.1% 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 — 91.5%
Publish DMARC — 77.1%
Enforce (quarantine or reject) — 48%
Reject (p=reject) — 26.1%

The story is the drop-off. Publishing SPF is nearly universal (91.5%) and DMARC adoption is high (77.1%) — but only 48% enforce anything (quarantine or reject), and just 26.1% 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.

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 Thu, 02 Jul 2026 08:16:19 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, 26.1% enforce DMARC with p=reject and 48% enforce at least quarantine.

Built & updated automatically by MailTester Ninja — the email verifier that stores nothing. DNS-only, aggregate data, no personal information. · Index · Email checker · Tools · Guides · Insights · JSON API · ✓ Verify an email address →