- Outlook was down for users across North America – and maybe other regions too
- Login, server connections and sending/receiving mail were all affected
- The issue was attributed to “unexpectedly high” CPU usage
A system outage affecting Outlook users across North America, which has now been resolved, caused users not to be able to access emails and calendars via any Exchange Online connection method.
The issue, tracked as EX1151485 in the admin center, was covered on the Microsoft 365 Status X page in a series of posts.
Microsoft declared that the “majority of previously degraded infrastructure” had been “restored” around 14 hours after the first post went out, but the company chose not to share further details about the outage.
Outlook has just come back online
The Outage started early Thursday morning (September 11) local times, with users noting issues across Outlook, Teams and Hotmail. Some noted OneDrive problems, too, but we’re not sure if these are connected.
Login issues and server connection problems were the key issues, but email delivery delays also caused headaches for many.
Within hours of posting its first X update, Microsoft reassured users that it was still “continuing to evaluate service telemetry for potential system irregularities.”
Downdetector saw spikes in complaints relating to Microsoft 365 and Outlook online, while the company’s public support page reported “service degradation on Microsoft consumer products.” For outlook, most complaints related to login, with server connection and sending receiving some remarks, too.
It later applied some “optimizations” which caused “some service improvements” before revealing that some users in South America had also been affected by the disruptions.
The fault has since been attributed to “unexpectedly high resource (CPU) utilization which may be contributing to connection errors and failures for mailboxes hosted on this portion of infrastructure,” determined by telemetry and trace logs analyzed by Microsoft’s engineers.
Microsoft continues to monitor the issue for any further signs, but for now, services remain “within expected thresholds.”
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