Reverse MX Lookup (Deprecated) API

{
  "query": {
    "mx": "aspmx.l.google.com",
    "match": "exact",
    "include_apex_only": true
  },
  "deprecated": true,
  "deprecation_notice": "This endpoint is deprecated. It only searches a best-effort seven-day passive index populated by prior /v1/dns/all lookups and capped at 10,000 recent entries per key. It is not an internet-wide reverse DNS dataset.",
  "results": [],
  "summary": {
    "total_found": 0,
    "returned": 0
  },
  "freshness_summary": {
    "source": "passive_dns",
    "cache_status": "passive_cache_only",
    "result_count": 0,
    "returned_count": 0,
    "apex_domain_count": 0,
    "apex_deduped_count": 0,
    "warning_count": 2,
    "warnings": ["passive_cache_only", "no_cached_matches"],
    "last_seen_span_days": null
  },
  "page": {
    "limit": 100,
    "next_cursor": null
  },
  "meta": {
    "source": "passive_dns",
    "note": "Best-effort seven-day index populated only by prior /v1/dns/all lookups"
  },
  "cache": {
    "hit": null,
    "age_s": null,
    "ttl_s": null,
    "key": null
  }
}