Is anyone else seeing problems with Microsoft 365 today, September 9? Emails that arrived yesterday are showing up as new again this morning, while the original deliveries seem to have disappeared. Several users are affected. We also use Proofpoint, but its status page does not show any problems.
4 Answers
There’s a Microsoft 365 service-health warning about elevated CPU usage and degraded search, which lines up with problems searching mail in Defender. The admin portal has also been slow or unreachable for some users.
We found a related issue with Jira notifications. Exchange started classifying older Jira messages as high-confidence phishing, quarantining them, and then automatically releasing them. That may explain the messages being redelivered.
Outlook on Mac is having additional trouble. New Outlook users are reporting that mail stops syncing and Copilot actions fail, while switching to legacy Outlook appears to work as a temporary workaround. Apple Mail also works with the same accounts, so this may be specific to the new Mac client.
That matches what we’ve reproduced on several Macs: legacy mode restores syncing for now, while the same accounts continue to fail in the new Outlook experience.
We’re seeing messages delivered twice, and message trace confirms duplicate deliveries. It appears to be affecting at least some tenants rather than being limited to one local mail system.
We found the same thing after digging further—so far, every duplicate we checked came from Jira.