Microsoft is testing a fix for a widespread, multi-hour outage that disrupted Outlook and other Exchange Online services, affecting email delivery, authentication and related functionality.
The company confirmed the disruption on Monday, saying users were experiencing degraded performance across its cloud-based Exchange Online platform, which supports business email, calendars, contacts and tasks.
Microsoft initially investigated reports of service failures before identifying an issue involving an authentication component.
The company is testing a remediation strategy on part of its infrastructure to determine whether it resolves the problem. If successful, Microsoft said it will deploy the fix more broadly.
The authentication issue was also found to be affecting services beyond Exchange Online, potentially expanding the scope of the disruption.
The outage underscores the growing dependence of businesses on cloud-based productivity platforms, where problems with core authentication infrastructure can have a wider impact across connected services.
