{
  "schema_version": "1.1",
  "id": "outlook-high-volume-senders-5000-spf-dkim-dmarc",
  "slug": "outlook-high-volume-senders-5000-spf-dkim-dmarc",
  "url": "https://groundedkit.com/claims/outlook-high-volume-senders-5000-spf-dkim-dmarc/",
  "api_url": "https://groundedkit.com/api/claims/outlook-high-volume-senders-5000-spf-dkim-dmarc.json",
  "claim": "Outlook requires SPF, DKIM and DMARC for domains sending more than 5,000 emails a day",
  "commonly_cited_as": "\"Microsoft's bulk-sender rules\"",
  "verdict": "verified",
  "verdict_definition": "Primary source found; it says the same thing, the scope matches, and it is reasonably current.",
  "confidence": "high",
  "rating": {
    "value": 5,
    "best": 5,
    "worst": 1
  },
  "origin": {
    "publisher": "Microsoft (Microsoft Defender for Office 365 blog)",
    "title": "Strengthening Email Ecosystem: Outlook’s New Requirements for High‐Volume Senders",
    "year": "2025"
  },
  "quote": "For domains sending over 5,000 emails per day, Outlook will soon require compliance with SPF, DKIM, DMARC. Non‐compliant messages will first be routed to Junk.",
  "method": "Microsoft announcement on its Tech Community blog.",
  "drift": [
    "Applies to Outlook consumer mailboxes (outlook.com, hotmail.com, live.com)"
  ],
  "interest": "Microsoft operates Outlook.",
  "safe_rephrasing": "Microsoft requires domains sending over 5,000 emails a day to Outlook consumer addresses to pass SPF, DKIM and DMARC; non-compliant mail goes to Junk first and may later be rejected.",
  "sources": [
    {
      "title": "Microsoft Tech Community — Outlook requirements for high-volume senders",
      "url": "https://techcommunity.microsoft.com/blog/microsoftdefenderforoffice365blog/strengthening-email-ecosystem-outlook%E2%80%99s-new-requirements-for-high%E2%80%90volume-senders/4399730",
      "primary": true
    }
  ],
  "kind": "reference_fact",
  "as_of": "Announced April 2025",
  "last_checked": "2026-10-17",
  "stale": false,
  "date_reviewed": "2026-10-17",
  "license": "CC BY 4.0",
  "license_url": "https://creativecommons.org/licenses/by/4.0/"
}