Microsoft is working to address an ongoing Exchange Online outage that is preventing customers from accessing their mailboxes and calendars.
“We’re investigating reports of some users experiencing issues when accessing their Exchange Online mailbox via one or more connection methods,” Microsoft said when it acknowledged the issue at 06:42 AM UTC.
As Microsoft explained in a Microsoft 365 admin center update under EX1253275, Outlook on the web, Outlook desktop, Exchange ActiveSync, and other Exchange Online connection protocols are all affected by this outage.
While the company said that “telemetry continues to show the issue is no longer occurring for affected users” and that its engineers are “continuing to monitor service health to assess whether any additional actions are required to ensure sustained recovery,” customers are still reporting issues accessing their email.
Right before publishing, the Office.com web portal was down and displayed the message “We are sorry, something went wrong. Please try refreshing the page in a few minutes.”
Microsoft is also investigating a separate outage affecting the Microsoft 365 Copilot web sign‑in page and Copilot web clients at office.com/chat and m365.cloud.microsoft, m365.cloud.microsoft/chat, and copilot.cloud.microsoft.
Customers who need to use Microsoft Copilot are advised to use one of the application-based Microsoft Copilot services, including the Microsoft Copilot desktop app, Copilot in Microsoft Teams, or Copilot in Office apps.
“We’ve identified that a section of service infrastructure is not processing traffic efficiently. We’re making configuration changes to remediate impact,” the company said in an admin center service alert (MO1253428).
In January, Microsoft mitigated another Exchange Online service outage that intermittently blocked users from accessing their mailboxes via the Internet Mailbox Access Protocol 4 (IMAP4).
Microsoft addressed a similar outage in November that blocked customers’ access to Exchange Online emails via the classic Outlook desktop client.
Update March 16, 14:20 EDT: Microsoft says that today’s Exchange Online outage has been mitigated.
“An underlying issue involving the supporting network infrastructure resulted in a service availability degradation across the Exchange Online connection methods,” it said in a new admin center update. “We’re continuing to investigate to determine the full root cause and will provide more information within the Post-Incident Report.
However, the company is still investigating the MO1253428 issue that is causing Office.com or the Microsoft 365 Copilot web sign‑in access problems.
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