Microsoft Investigates New Exchange Online Outage
Microsoft is actively investigating a new disruption impacting Exchange Online, identified as EX1464935, affecting mail flow and user access.
Microsoft has initiated an investigation into a fresh outage affecting its cloud-based email service, Exchange Online. The incident, cataloged as EX1464935 in the Microsoft 365 admin center, began on August 31, 2026, at approximately 9:23 PM IST. Engineers were promptly engaged to address user reports of access and mail-flow disruptions.
As of the latest updates, the issue remains in the 'Investigating' status, indicating that Microsoft has not yet pinpointed the exact root cause or the full extent of the outage. While the advisory currently specifies only Exchange Online, past incidents have shown that such disruptions can sometimes expand to related Microsoft 365 services like Outlook and Teams before being contained.
This is not an isolated event for Exchange Online, which has experienced several disruptions in recent months. Earlier this year, a similar incident (EX1454755) was attributed to a DNS fault within a third-party email provider, rather than Microsoft's own infrastructure. In June, a separate issue within the mail-flow pipeline led to significant delivery delays across multiple continents, with some emails taking over an hour to reach their recipients.
Organizations heavily reliant on Exchange Online for their business communications are advised to closely monitor the Microsoft 365 admin center for official updates. It is recommended not to assume a widespread outage until confirmed, as many recent incidents have proven to be geographically limited or dependent on external factors.
IT administrators experiencing user-reported issues with delayed or missing messages are encouraged to check mail queues, delivery reports, and network connectivity status. Microsoft has committed to providing further information as its engineering teams continue to analyze mail-flow diagnostics and telemetry data to identify the source of the current disruption.
The ongoing nature of these incidents highlights the critical importance of robust monitoring and rapid response capabilities for cloud-based email services. Users and administrators alike are keenly awaiting a swift resolution to restore full service functionality and prevent further impact on business operations.