Summary (tl;dr)

Microsoft Outlook is experiencing a widespread service outage, causing email delivery delays, authentication issues, and problems accessing the platform for tens of thousands of users globally. Microsoft is investigating the disruption, identified as incident EX1464935.

Essential Background

Microsoft Outlook is a crucial email and personal information manager, widely used by individuals and businesses globally as part of the Microsoft 365 suite. It relies on Exchange Online for mailbox access and email delivery. When such a core communication service experiences an outage, it can severely disrupt daily operations, productivity, and essential communications for its vast user base.

The Full Story

On Monday, August 31, 2026, Microsoft Outlook began experiencing significant service disruptions, leading to a surge in user reports on outage tracking sites like Downdetector. Reports peaked around 9:30 AM PT, with thousands of users unable to send or receive emails, facing authentication errors, and encountering difficulties accessing the Exchange Online platform. Microsoft officially acknowledged the issue, tracked as incident EX1464935 in the admin center, and confirmed an issue with an authentication component contributing to the impact. Engineers are currently reviewing service telemetry and diagnostic data to isolate the source and are applying a remediation strategy to address the problem. While the primary focus is on Exchange Online and Outlook, some users have also reported issues with other Microsoft services, including Azure, Teams, and the Microsoft Store.

Why It Matters

This widespread Outlook outage is significantly impacting business operations and personal communications for a large number of users who depend on Microsoft's email services. The inability to send or receive critical emails, coupled with authentication failures, can lead to lost productivity, missed deadlines, and communication breakdowns across various sectors. The incident highlights the critical reliance on cloud-based services for daily functionality and the far-reaching consequences when these systems encounter technical difficulties.

Geographic Location

• None (The outage is a widespread service disruption affecting users globally, without a single specific physical location for the event itself)