Microsoft has opened an active investigation into a new Exchange Online disruption after a wave of user reports flagged access and mail-flow problems across the cloud-based email service.
The incident, logged in the Microsoft 365 admin center as EX1464935, began at 9:23 PM IST on August 31, 2026, with the company confirming at 9:25 PM IST that engineers were “investigating user reports of Exchange Online issues”.
As of the latest update, the status remains listed as “Investigating,” meaning Microsoft has not yet isolated a root cause or confirmed the scope of the disruption.
The advisory currently names Exchange Online as the sole affected service, though early-stage incidents of this kind have, in past cases, sometimes widened to touch related Microsoft 365 workloads such as Outlook and Teams before being narrowed down. Administrators can track granular, tenant-specific details through the Service Health Dashboard in the Microsoft 365 admin center.
This is not the first time Exchange Online has stumbled in recent months. Earlier in this year, Microsoft traced a similar user-facing incident, EX1454755, to a DNS-related fault inside a third-party email provider rather than its own infrastructure.
In June, a separate mail-flow pipeline issue caused widespread delivery delays across North America, Europe, and Asia-Pacific, with some messages stuck undelivered for over an hour.
For now, organizations relying on Exchange Online for business email should monitor the admin center for updates rather than assume a widespread outage, since many recent incidents have turned out to be regionally limited or tied to third-party dependencies.
IT teams are advised to check mail queues, delivery reports, and connectivity status if users report delayed or missing messages. Microsoft has committed to posting further updates as its engineers analyze mail-flow diagnostics and telemetry to determine the source of the disruption.
Update: Microsoft confirms users may experience degraded functionality with various Exchange Online functionalities.
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