Mail server reverse DNS · UK medium & large companies
What share of UK medium & large companies have a mail server with no reverse-DNS (PTR) record?
3.48% of UK medium & large companies (95% CI 2.26–5.31%), measured across 575 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. Resolve the MX, then PTR on the reversed address (bounded DNS query). 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
Missing reverse DNS is a classic quiet failure — nothing breaks visibly, but receiving mail systems downgrade or reject on it, so outbound deliverability degrades in ways that surface as "our email sometimes doesn't arrive".
The same check, other segments
- France small companies10.12%
- France micro companies9.05%
- France companies8.45%
- France large companies8.43%
- UK newly-formed (no accounts filed) companies8.33%
- France medium companies5.67%
- global domains5.46%
- UK small companies5.3%
Show the remaining 7 segments
- UK companies4.8%
- Norway medium companies4.05%
- UK micro companies3.94%
- Norway micro companies3.79%
- Norway large companies3.75%
- Norway companies3.19%
- Norway small companies1.26%