Microsoft 365 Outage: What Happened and What We Know
Microsoft 365 has been disrupted since Thursday 12 November, and email, calendars and meetings across the UK and beyond are still feeling it. If your inbox has been quiet, or your Teams invites have gone missing, you are not alone. Here is what we know and what Microsoft is doing about it.
What has gone wrong
The trouble started on Thursday with Exchange Online problems around 11:17 a.m. ET, widening into a broader Microsoft 365 outage by 1:26 p.m. ET. Outlook and Exchange Online were hit hardest, with users struggling to open mailboxes, send email or receive messages.
The knock-on effects reached well beyond email:
- Microsoft Teams: mainly calendar and meeting scheduling, although messaging and calling worked for many users.
- Microsoft 365 Copilot: some users could not access chats or retrieve information.
- Business services: SharePoint Online, Defender XDR, Intune, Planner and To Do.
- Consumer services: Outlook.com, OneDrive, OneNote and Microsoft 365 for the web, to varying degrees.
Microsoft first suspected unusually high traffic. Further investigation found that several backend servers had unexpectedly become unavailable, leaving the remaining servers overloaded. Servers restarted during recovery then became unresponsive again once traffic returned. Microsoft says there is no sign of malicious activity.
Recovery is under way but incomplete. Some servers are back and stable, though capacity is still below normal, and a patch aimed at an authentication and routing component appears to be helping. Microsoft has not given an estimated time for full restoration. To protect delayed messages, it has extended its email timeout window to 48 hours.
This outage is also a reminder that one provider should not be a single point of failure for the way your business communicates.
Notice for existing clients: Webex services are not affected by this outage and are operating as normal.
