Measurements we ran ourselves, with the method and the raw counts published alongside.
Most writing about cold email repeats numbers nobody can trace. We publish the opposite: measurements taken from sources anyone can query, with the method stated plainly enough that you can reproduce the result and disagree with it.
Every study here says what it did not measure as clearly as what it did.
We read the public SPF, DKIM and DMARC records of 156 B2B lead generation, appointment setting and outbound agency domains. Eighty-seven carry at least one real defect on their own domain. Only 30 enforce DMARC at p=reject, ten publish no SPF record at all, and four publish two or more SPF records, which is a permanent error that makes SPF fail outright. No agency is named for a defect. The 69 clean ones are named.
The deliverability checker runs the same reading these studies are built on, live in your browser, against Cloudflare's public resolver. It names the service that actually sends your mail, flags duplicate records, and reports your DMARC policy without guessing.