Microsoft is racing to resolve a widespread Outlook outage that hit users during peak U.S. business hours Thursday, just months after a 21-hour email meltdown tested enterprise patience. The disruption, which began around 2:37 p.m. ET, prevented users from sending or receiving messages while also slowing OneDrive and SharePoint searches. With Outlook serving as the backbone of Microsoft 365 productivity suites across schools, government agencies, and corporations, the timing amplified frustration as workers took to social media to vent about the service interruption.
Microsoft scrambled to contain an Outlook email outage Thursday that struck in the middle of U.S. business hours, disrupting communications for enterprises, schools, and government agencies relying on the productivity platform. Users across North America found themselves locked out of email at 2:37 p.m. ET, triggering a wave of social media complaints as the workday ground to a halt.
The company acknowledged the issue on its service status dashboard, revealing that users were encountering '451 4.3.2 temporary server issue' error messages when attempting to send or receive email through Outlook. The problem wasn't isolated to email - OneDrive cloud storage searches and SharePoint Online collaboration features were also running slow or failing entirely, according to Microsoft's update.
For the thousands of organizations that have standardized on Microsoft 365, the disruption hit hard. Outlook sits at the center of daily workflows, handling everything from client communications to internal coordination. Schools trying to reach parents, businesses managing customer relationships, and government offices processing constituent requests all found themselves cut off from their primary communication channel.
By 3:17 p.m. ET, Microsoft had identified the culprit: a portion of service infrastructure in North America wasn't handling traffic correctly. The admission revealed the kind of infrastructure failure that can cascade across Microsoft's massive cloud operation, where millions of users depend on seamless service delivery.
