{
 "metric": "smtp-starttls",
 "segment": "gb-small",
 "anchor": "company",
 "label": "UK small companies",
 "population": "UK small companies",
 "states": [
  "offered",
  "absent"
 ],
 "quiet_failure_states": [
  "absent"
 ],
 "measurement": "Connect to the lowest-preference MX on port 25, `EHLO`, check for the `STARTTLS` capability. Denominator: `has_mx`, further restricted to MXs that answer.",
 "why_it_matters": "If STARTTLS is not offered, every inbound message crosses the internet in plaintext, readable by anything on the path. The domain may have perfect SPF/DMARC and still be handing its mail over in the clear.",
 "limits": "~32% of small-company MXs never answer within a 6s timeout and are excluded, so this is measured over *reachable* mail servers.",
 "data_tier": "smtp",
 "population_predicate": "has_mx",
 "entity_type": "domain",
 "kind": "failure",
 "latest": {
  "day": "2026-08-14",
  "n": 405,
  "qf_pct": 2.72,
  "ci": [
   1.52,
   4.8
  ],
  "dist": {
   "offered": 97.28,
   "absent": 2.72
  },
  "snapshot": "uk-companies-house-per600-seed20260728"
 },
 "series": [
  {
   "day": "2026-08-02",
   "n": 353,
   "qf_pct": 1.98,
   "ci": [
    0.96,
    4.04
   ],
   "dist": {
    "offered": 98.02,
    "absent": 1.98
   },
   "snapshot": "uk-companies-house-per300-seed20260728"
  },
  {
   "day": "2026-08-04",
   "n": 408,
   "qf_pct": 2.7,
   "ci": [
    1.51,
    4.76
   ],
   "dist": {
    "offered": 97.3,
    "absent": 2.7
   },
   "snapshot": "uk-companies-house-per600-seed20260728"
  },
  {
   "day": "2026-08-05",
   "n": 409,
   "qf_pct": 2.69,
   "ci": [
    1.51,
    4.75
   ],
   "dist": {
    "offered": 97.31,
    "absent": 2.69
   },
   "snapshot": "uk-companies-house-per600-seed20260728"
  },
  {
   "day": "2026-08-07",
   "n": 403,
   "qf_pct": 2.73,
   "ci": [
    1.53,
    4.82
   ],
   "dist": {
    "offered": 97.27,
    "absent": 2.73
   },
   "snapshot": "uk-companies-house-per600-seed20260728"
  },
  {
   "day": "2026-08-14",
   "n": 405,
   "qf_pct": 2.72,
   "ci": [
    1.52,
    4.8
   ],
   "dist": {
    "offered": 97.28,
    "absent": 2.72
   },
   "snapshot": "uk-companies-house-per600-seed20260728"
  }
 ],
 "license": "CC BY 4.0",
 "source": "https://quietfailures.com/datasets/smtp-starttls/gb-small"
}