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DMARC, sender rules and the bounces that follow
New rules from the mailbox providers, what their bounces mean, and the path from p=none to p=reject. For how DMARCLoop works, see the help centre.
- Update: the Outlook.com rejections were a Microsoft fault, now fixed Microsoft says a faulty spam-rule update caused this week's Outlook.com and Hotmail rejections, and has rolled it back. What changed, and what still matters.
- Why is Outlook.com rejecting our email with "Message lacks SPF/DKIM/DMARC Auth Records"? Outlook.com and Hotmail began rejecting some mail from domains with no DMARC record in November 2026. What the bounce means, who it affects, and the fix.
- Gmail, Yahoo and Microsoft sender rules in one table (2026) What Gmail, Yahoo and Outlook.com require of senders in 2026: SPF, DKIM, DMARC, spam rates and unsubscribe, the volume thresholds, and the bounces you get.
- Reading a DMARC bounce: 5.7.1, 5.7.509, 5.7.515, 5.7.26 and friends What each authentication bounce from Gmail, Outlook.com and Microsoft 365 means, and the fix for each: 5.7.26, 5.7.509, 5.7.515, 5.7.1 and the rest.
- p=none isn't protection: a 60-day path from p=none to p=reject p=none gets your mail delivered but stops nobody sending as you. A 60-day path to p=reject: quarantine by day 30, reject from day 60, and what each step needs.
- Microsoft 365 DKIM: why your domain's mail isn't signed, and how to fix it Microsoft 365 doesn't DKIM-sign mail from your own domain until you turn it on, so DMARC rests on SPF alone. How to find out, and the two records that fix it.
- Your invoicing tool is sending as your domain: auditing third-party senders CRMs, helpdesks, invoicing and payroll tools send as your domain and often fail DMARC alignment. How to find them in your reports and fix each one.