{
 "metric": "mta-sts",
 "segment": "gb-medium-large",
 "anchor": "company",
 "label": "UK medium & large companies",
 "population": "UK medium & large companies",
 "states": [
  "enforce",
  "testing",
  "absent"
 ],
 "quiet_failure_states": [
  "testing",
  "absent"
 ],
 "measurement": "Tier 0 + 3a. TXT at `_mta-sts.<domain>`; if present, fetch `https://mta- sts.<domain>/.well-known/mta-sts.txt` and read `mode`. Denominator: `has_mx`.",
 "why_it_matters": "The declared-vs-enforcing split is exactly the brand thesis. `mode: testing` publishes a policy, produces reports, and does not require TLS — downgrade attacks still work. The DNS record alone looks like adoption; only the fetched policy reveals whether it bites.",
 "limits": null,
 "data_tier": "dns",
 "population_predicate": "has_mx",
 "entity_type": "domain",
 "kind": "failure",
 "latest": {
  "day": "2026-08-10",
  "n": 1025,
  "qf_pct": 99.12,
  "ci": [
   98.34,
   99.54
  ],
  "dist": {
   "enforce": 0.88,
   "testing": 0.78,
   "absent": 98.34
  },
  "snapshot": "uk-companies-house-per600-seed20260728"
 },
 "series": [
  {
   "day": "2026-08-01",
   "n": 555,
   "qf_pct": 98.92,
   "ci": [
    97.66,
    99.5
   ],
   "dist": {
    "enforce": 1.08,
    "testing": 0.72,
    "absent": 98.2
   },
   "snapshot": "uk-companies-house-per300-seed20260728"
  },
  {
   "day": "2026-08-03",
   "n": 555,
   "qf_pct": 98.92,
   "ci": [
    97.66,
    99.5
   ],
   "dist": {
    "enforce": 1.08,
    "testing": 0.72,
    "absent": 98.2
   },
   "snapshot": "uk-companies-house-per300-seed20260728"
  },
  {
   "day": "2026-08-05",
   "n": 1025,
   "qf_pct": 99.12,
   "ci": [
    98.34,
    99.54
   ],
   "dist": {
    "enforce": 0.88,
    "testing": 0.68,
    "absent": 98.44
   },
   "snapshot": "uk-companies-house-per600-seed20260728"
  },
  {
   "day": "2026-08-10",
   "n": 1025,
   "qf_pct": 99.12,
   "ci": [
    98.34,
    99.54
   ],
   "dist": {
    "enforce": 0.88,
    "testing": 0.78,
    "absent": 98.34
   },
   "snapshot": "uk-companies-house-per600-seed20260728"
  }
 ],
 "license": "CC BY 4.0",
 "source": "https://quietfailures.com/datasets/mta-sts/gb-medium-large"
}