Is anyone else seeing problems with Microsoft 365 today? Emails that arrived yesterday are showing up as new messages again this morning, while the original deliveries seem to have disappeared. Multiple users are affected. We use Proofpoint, but its status page does not show any problems. I'm also wondering whether the issue is related to Exchange, Defender, Outlook for Mac, or the Microsoft 365 service itself.
4 Answers
Our investigation points to Jira notifications. Exchange is classifying older Jira messages as high-confidence phishing, quarantining them, and then automatically releasing them later, which makes them look like new deliveries.
There’s a Microsoft 365 service health alert mentioning high CPU usage and degraded search. Searching messages in Defender has been unreliable, and the Microsoft 365 admin portal was also slow or unreachable for some users.
Outlook for Mac is having separate problems as well. New Outlook is failing to sync, and Copilot’s rewrite feature returns an error. Switching to legacy Outlook appears to work as a temporary workaround, while the same accounts continue working in Apple Mail.
I’ve reproduced the Mac sync issue on several systems. Legacy mode is currently the only reliable workaround I’ve found.
We’re seeing duplicate deliveries too. Message trace shows the same messages being delivered twice, so this appears to be more than just an Outlook client display issue.
That matches what we found too—the duplicate messages all seem to be coming from Jira.