Defaults.Exposed › Stats › Email authentication (SPF, DKIM, DMARC)
How many mail-receiving domains lack email authentication?
October 2026 census edition
As of October 12, 2026, 29,970,338 domains that resolve mail exchangers publish neither SPF (Sender Policy Framework) nor DMARC (Domain-based Message Authentication, Reporting and Conformance): 9.0% of all graded domains receive email with no authentication published.
MX but no SPF/DMARC: how it is measured
It comes from the cross-check pass, which takes the per-domain results and counts the combinations: domains holding one control but not another, and domains holding a whole set together. Every domain in the census is measured directly and counted once.
This narrows to domains that actually receive mail, which is the population where the absence matters most. A domain with no MX records and no authentication is untidy; a domain that runs a live mailbox with no authentication can be impersonated freely, and its MX records show that someone reads the mail sent to it.
The figure is an absolute count of domains rather than a sample scaled up. A domain the census could not decide on is left out rather than estimated.
It moves when domain owners publish, correct or remove the DNS (Domain Name System) records that authenticate their mail. Every one of those records is free and takes minutes to publish, and together they decide whether someone else can send mail as the domain. The number is recomputed from the raw evidence at every edition. What it cannot tell you is where one particular domain stands: for that, see fix your email authentication.
the full grading methodology · the underlying dataset, published open with the counts behind every percentage. If a figure here disagrees with one elsewhere on the site, the dataset is canonical and we would like to know.
MX but no SPF/DMARC: how to cite it
Please cite Defaults.Exposed and link this page. The citation below carries the date.
Defaults.Exposed, "How many mail-receiving domains lack email authentication?" (as of October 12, 2026). https://defaults.exposed/stats/how-many-mail-domains-lack-authentication
Permalink: https://defaults.exposed/stats/how-many-mail-domains-lack-authentication · Machine-readable: /stats/s/mx-no-auth.json · Licence: open data
Methodology: how we grade the internet · Source data: census data and downloads. Updated with each census edition.