Is Outlook Down? Microsoft Investigates Exchange Online Failures as Thousands Report Email Problems
Thousands of users have reported problems with Microsoft Outlook as Microsoft investigates a new Exchange Online disruption affecting email services. Receiving messages is among the biggest reported problems.
Some users are also reporting trouble accessing Outlook and Exchange Online. Microsoft has not separately listed Outlook as an affected service, leaving the scope of the disruption unclear.
Microsoft Investigates Exchange Online
Microsoft logged the incident as EX1464935 in the Microsoft 365 admin center. It began at 9:23 p.m. IST on Aug. 31, 2026.
The incident followed reports of access and mail-flow problems, with Microsoft confirming its investigation two minutes later. Engineers are examining Exchange Online but have not identified the underlying cause.
The latest status remains ‘Investigating,’ while Microsoft has not confirmed the full scope of the disruption. The company has not said when the issue will be resolved.
The advisory currently lists Exchange Online as the sole affected service. The reported Outlook problems have not been officially described as a separate affected service.
Microsoft has confirmed that users may experience degraded functionality across Exchange Online. Reported symptoms include delays or failures when sending or receiving email messages.
Authentication-related errors have also been reported when accessing Exchange Online services. Users have also experienced difficulties with mailbox operations and message-delivery workflows.
According to outage-tracking service Downdetector, tens of thousands of Exchange Online users have been affected. Reports include problems receiving email through Outlook and accessing the Exchange Online platform.
Administrators can use the Service Health Dashboard in the Microsoft 365 admin center. It provides tenant-specific details that can help organizations assess their own service status.
Exchange Online Faces Fresh Disruption
The current incident is not the first Exchange Online problem in recent months. Earlier this year, Microsoft investigated another user-facing incident identified as EX1454755.
Microsoft traced that earlier incident to a DNS-related fault inside a third-party email provider. The problem was not traced to Microsoft’s own infrastructure.
In June, a separate mail-flow pipeline issue caused widespread delivery delays. The disruption affected North America, Europe and Asia-Pacific.
Some messages remained undelivered for more than an hour during that incident. Those earlier problems do not establish a cause for the latest disruption.
Microsoft has not confirmed any connection between those incidents and the current investigation. Engineers are analyzing service telemetry and diagnostic data to determine the source of the latest problem.
For organizations that rely on Exchange Online for business email, delayed messages can create immediate problems. IT teams can check mail queues, delivery reports and connectivity status.
Those checks can help organizations determine whether messages are delayed or missing. They can also help IT teams track the impact while Microsoft investigates.
For now, organizations should monitor the Microsoft 365 admin center for further information. They should not assume that all Microsoft 365 services are affected.
The latest reports place email delivery and authentication problems at the center of the disruption. Microsoft has not confirmed that Outlook itself is a separately affected service.
The investigation therefore leaves two issues unresolved: the cause of the disruption and its full scope. Microsoft has yet to confirm how broadly users are being affected.
For users unable to receive messages, the lack of a resolution time adds uncertainty. Further Microsoft updates should provide more information about the Exchange Online disruption.
