Defaults.Exposed › Methodology › v7 registry › DKIM
DKIM
Methodology v7 · canonical ID dkim-exists · Email Security · scored · census as of July 28, 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
51.2% of graded domains have a discoverable DKIM selector (37,762,161 of 73,825,298, as of July 28, 2026).
Selector discovery is best-effort: an unobserved selector does not prove DKIM is unused, so this is a lower bound.
Census denominator: 275,666,275 graded domains. Aggregates only — never an individual domain's result.
Fix it
Plain-English impact, cost of ignoring it, and step-by-step remediation: defaults.exposed/en/fix/dkim
Cite this check
Defaults.Exposed, "DKIM (dkim-exists)", Grading Methodology v7 (census as of July 28, 2026). https://defaults.exposed/methodology/v7/dkim-exists
Permalink: https://defaults.exposed/methodology/v7/dkim-exists ·
All 34 checks: v7 registry ·
Machine-readable: checks.json ·
Licence: open data