Defaults.Exposed › September 2026 census › v10 registry › DKIM
DKIM
Methodology v10 · canonical ID dkim-exists · Email Security · scored · census as of September 5, 2026
A cryptographic signature proving mail is genuinely from you; boosts deliverability.
Definition
| Canonical ID | dkim-exists |
|---|---|
| Category | Email Security |
| Grade impact | Scored, counts toward the grade |
| Pass | A DKIM public key is discoverable at a common selector under _domainkey.<domain>. |
| Fail | No DKIM selector is observable at the probed selectors. |
| Example (passing) | selector1._domainkey.example.com TXT "v=DKIM1; k=rsa; p=MIIBIjANBg…" |
No-data rule: when this check couldn't be determined for a domain (timeout, SERVFAIL, redacted source) it returns N/A and is excluded from that domain's scoring denominator: "couldn't determine" is never counted as a failure. "Determined absent" is a real fail.
Prevalence across the census
50.1% of domains where a DKIM selector could be determined publish one (37,999,462 of 75,823,110, as of September 5, 2026).
The census probes a fixed list of common selectors, so a domain signing under an unguessed selector reads as not-determinable, never as absent. Treat this as a floor.
Census denominator: 316,600,902 graded domains; this check is measured only against domains where a DKIM selector could be determined (75,823,110). Aggregates only: never an individual domain's result.
Fix it
Plain-English impact, cost of ignoring it, and step-by-step remediation: defaults.exposed/fix/dkim
Cite this check
Defaults.Exposed, "DKIM (dkim-exists)", Grading Methodology v10 (census as of September 5, 2026). https://defaults.exposed/v10/methodology/dkim-exists
Permalink: https://defaults.exposed/v10/methodology/dkim-exists ·
All 34 checks: v10 registry ·
Machine-readable: /v10/methodology/checks.json ·
Licence: open data