← 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.

Free deliverability tools → Check any domain (MX, SPF, DMARC), test your own inbox placement scored out of 100, generate SPF and DMARC records, or run a blocklist check, all free with no signup and nothing stored, at deliverability.mailtester.ninja/tools.

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.

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

Built & updated automatically by MailTester Ninja, the email verifier that stores nothing. DNS-only, aggregate data, no personal information. · JSON API · RSS