Microsoft says it will expand corrective measures to tackle a global outage affecting Outlook and several Microsoft 365 services for over seven hours, as it monitors the stability of changes already applied to affected servers.In its latest update, Microsoft said it was monitoring the affected servers after implementing temporary traffic restrictions in specific locations.The company said it would gradually reintroduce additional traffic once it confirmed that the servers remained stable while handling a narrower set of connections. It also said corrective measures would be expanded as stability was established with the changes already applied.Microsoft's investigation found that a process responsible for establishing secure connections on the affected servers was becoming overwhelmed, causing the servers to stop processing requests.
The company is preparing a configuration change to address the problem across all affected servers. It is first validating the change on a subset of servers before applying it more widely, alongside restarts of the affected infrastructure.In parallel, Microsoft has begun reverting a recent network configuration change that coincided with the start of the disruption.
It is monitoring whether reversing that change contributes to recovery. The outage has affected several Microsoft 365 services and features that interact with Exchange Online and email services.
Microsoft said elements of these services that do not depend on Exchange Online remain functional.Users may be unable to access their mailboxes through Outlook on the web, Outlook desktop, Exchange ActiveSync or REST-based connections, while email delivery may also be delayed. Some Microsoft 365 admin centre pages may not load, and users may be unable to view recently used files in Microsoft 365 apps.Microsoft Copilot Chat users may be unable to load the service or receive responses through web and desktop apps.
Copilot may also be unable to access work data, including emails, calendars and files.Other affected services and features include Microsoft Planner, Microsoft To Do, Microsoft Purview, Microsoft Defender, Microsoft Graph, Power BI, Universal Print and certain Windows 365 functions.Microsoft Teams features that depend on Exchange Online, including calendars and meeting scheduling, may also fail. However, the company said core messaging and online meetings remain largely functional.
Access to files stored directly in SharePoint Online also remains functional.Microsoft said it was continuing to monitor the affected servers and assess the impact of the corrective measures.- Ends