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Delivery flaky at Gmail and Outlook, SPF/DKIM/DMARC are separate, want them as a coherent bundle

Since Google and Yahoo tightened delivery rules (February 2024), having all three is required for senders above 5000 mails/day and recommended for everyone. SPF protects envelope-from, DKIM signs the message, DMARC tells receivers what to do on failure.

Try this first

  1. 1Start with SPF: one TXT at apex, 'v=spf1 include:<provider> include:<other-sender> ~all'. Do not stack, stay under 10 DNS lookups.
  2. 2DKIM: let every sender (M365/Google/Mailgun/Postmark/SendGrid) create its own selector, place the CNAME or TXT as specified, and only enable in the portal after DNS resolves.
  3. 3DMARC: TXT at _dmarc.yourdomain, start with 'v=DMARC1; p=none; rua=mailto:dmarc@yourdomain; pct=100'. Read reports for 2 weeks before tightening.
  4. 4Move to p=quarantine with pct=10, then 50, then 100, until no legitimate mail lands in quarantine.
  5. 5End state p=reject once all sources are aligned. Then nobody sends on your behalf and spoofing is actively rejected.

When to bring us in

If you have many senders and no overview which system is aligned, we plan a DMARC rollout with reporting so you can move to reject in phases.

See also

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