Microsoft worked to restore Outlook and other Microsoft 365 services on Friday after a widespread outage disrupted mailbox access and connectivity across multiple regions.
Users initially reported problems in the Americas on Thursday. Microsoft subsequently warned that the disruption could affect customers in any region.
In a Friday update, Microsoft said a recovery change was “not taking as expected”. Engineers were assessing alternative ways to restore capacity and address traffic imbalances.
Exchange Online, which supports business email accessed through Outlook, remained central to the investigation. Microsoft’s incident notices described problems connecting to mailboxes through web, desktop and mobile connection methods.
Some users could not load their inboxes, while others experienced delayed email delivery.
Downdetector recorded more than 120,000 reports during the early afternoon in the US. Those submissions measure reported problems rather than a verified count of affected customers.
Microsoft initially said automated recovery systems had begun restoring service and reducing the impact. However, later incident updates described servers becoming unresponsive again after engineers returned them to service and traffic resumed.
Engineers redirected connections, restarted affected infrastructure and tested configuration changes. Microsoft attributed the pressure on remaining infrastructure to servers becoming unavailable, rather than an overall increase in traffic.
Other affected functions included features in Teams, SharePoint Online, Microsoft 365 Copilot and Microsoft Defender XDR. Microsoft clarified that some functions dependent on Exchange Online could fail while unrelated features continued working.
Read More: Google Cloud Outage Hits London as Banks Report Issues
A separate Teams disruption earlier on Thursday had already ended. Microsoft had not established a connection between that incident and the broader outage.
Administrators can follow the investigation through Microsoft’s service-health dashboard under incident references EX1550543 for Exchange Online and MO1550821 for the wider disruption.
