Mail server reverse DNS · UK dormant companies
What share of UK dormant companies have a mail server with no reverse-DNS (PTR) record?
10.19% of UK dormant companies (95% CI 5.78–17.32%), measured across 108 companies on 2026-08-14.
Measured every Friday since 2026-08-01 — 6 observations to date. Last measured 2026-08-14.
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 micro companies8.65%
- France medium companies8.56%
- France small companies8.09%
- France companies7.83%
- UK newly-formed (no accounts filed) companies7.14%
- France large companies5.71%
- global domains5.13%
- UK medium & large companies5%
Show the remaining 8 segments
- UK companies4.83%
- UK micro companies4.58%
- UK small companies3.15%
- Norway small companies1.75%
- Norway micro companies1.2%
- Norway companies1.14%
- Norway medium companies0.85%
- Norway large companies0.61%