A rough week, but we survived

Whew. What a week it’s been. Two separate Microsoft issues in the span of seven days had email senders and admins scratching their heads, saw mail unexpectedly rejected, and left users temporarily locked out of their inboxes. Let’s recap what happened, and then talk about what it means for you. First Issue: DMARC Rejections (November 6-9) Starting Friday night, November 6th, email admins on the Mailop list and elsewhere began reporting that Microsoft was rejecting mail sent to Outlook.com and Hotmail recipients when the sending domain had no DMARC record. It didn’t matter if the message passed SPF and DKIM. No DMARC record? Bounce, with a 550 5.7.1 error stating that the message lacked SPF/DKIM/DMARC auth records. This only hit Microsoft’s consumer mailboxes (outlook.com, hotmail.com, live.com, msn.com and friends), not Microsoft 365 business tenants. I confirmed it myself on Saturday. In my tests, mail to outlook.com bounced, while mail to a Microsoft 365-hosted domain delivered. By…

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