Microsoft struggles to restore Exchange Online after widespread outage hits global users

A widespread outage struck Microsoft 365 on Thursday, disrupting access to Outlook, Exchange Online, Microsoft Teams, and Copilot for customers around the world. Tracked internally under advisory MO1550821, the disruption began at 1:26 PM ET following earlier mailbox connectivity issues in the Americas. Microsoft stated that the problem stemmed from servers unexpectedly failing automated health checks and becoming unavailable rather than an external surge in traffic, leaving the remaining infrastructure strained. [1][3][4]

The failure primarily knocked offline Microsoft 365 platforms that interact with Exchange Online, though services independent of email systems remained functional. To resolve the disruption, the company paused deployments, rerouted global connections, and attempted to scale up virtual machines. However, Microsoft reported that these recovery efforts faced repeated hurdles, including newly provisioned machines getting stuck in a bad state and failing to sync changes properly. [1][4]

The incident extended well beyond 12 hours, severely interrupting business operations in regions like Australia heading into Friday. Microsoft confirmed it had found no evidence that malicious cyber activity caused the failure, though it did not specify when full functionality would be restored. [1][2][4]