DANE for mail · UK small companies
What share of UK small companies have no DANE/TLSA record binding their mail server's certificate?
98.4% of UK small companies (95% CI 96.98–99.16%), measured across 562 companies on 2026-10-01.
Measured every Friday since 2026-08-01 — 12 observations to date. Last measured 2026-10-01.
How this is measured
Tier 0 (DNS-only, so it works even where port 25 is blocked). TLSA lookup at _25._tcp.<mx>. Denominator: has_mx.
Passive measurement: a single DNS lookup, TLS handshake, or homepage GET per domain. Aggregate-only; no individual company is named. 95% Wilson confidence intervals. Population: national company registries (Companies House, Brreg, SIRENE), sampled by size band and resolved to email-active domains. Parked domains excluded. Snapshot: uk-companies-house-per600-seed20260728.
Licensed CC BY 4.0 — reuse with attribution to Quiet Failures. Download: JSON · CSV.
Why it matters
DANE is what turns opportunistic TLS into authenticated TLS — it tells a sender which certificate to expect, closing the downgrade gap that mx-tls-cert exposes.
Limits of this measurement
Near-universally absent outside a few countries; useful as an adoption frontier rather than an actionable defect for a small company.
The same check, other segments
- France medium companies100%
- France large companies99.41%
- France companies98.58%
- UK micro companies98.44%
- UK medium & large companies98.28%
- France micro companies98.23%
- UK companies97.98%
- France small companies97.2%