Mail server reverse DNS · global domains
What share of domains worldwide have a mail server with no reverse-DNS (PTR) record?
5.46% of domains worldwide (95% CI 4.41–6.75%), measured across 1,464 domains 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: domains sampled from the Common Crawl web graph, filtered to those that do email. Parked domains excluded. Snapshot: common-crawl-domain-stratified-c400-g2500-seed20260729.
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%
- UK small companies5.3%
- UK companies4.8%