Microsoft investigates Outlook outage linked to Exchange Online authentication issue
Microsoft confirmed an outage affecting Outlook services due to an authentication component problem in Exchange Online, and is testing a remediation on its infrastructure.
Thousands of Outlook users reported being unable to access email on Monday morning, with outage monitoring site Down Detector logging more than 6,000 reports by 8:17 a.m. PT. Microsoft acknowledged the issue, stating that an authentication component in Exchange Online was causing the disruption. The company said it had developed a remediation strategy, which it was testing on part of its infrastructure before a broader rollout. The incident has been logged under reference EX1464935 in the Microsoft 365 admin center. Down Detector data indicated that 37% of affected users experienced problems receiving messages, 23% had trouble using the Outlook app, and 20% reported issues with the Outlook website.