Office Workers Cut Off From Email and Chat as Microsoft Teams Falters Twice and Outlook Goes Dark for Hours

Microsoft Teams suffered a separate disruption on Thursday 12 November, before an Outlook outage cut off work email for users across the Americas and beyond. Microsoft resolved the Teams fault before the email problem spread to other Microsoft 365 services. Outage tracker Downdetector logged nearly 130,000 Outlook problem reports at the peak, shortly after 6pm UK time.

The failure hit Exchange Online, the service behind work and school Outlook accounts. Some SharePoint Online and Microsoft 365 Copilot features were affected too. Microsoft blamed servers that unexpectedly dropped out of service. It said users in any region could be affected. By Thursday evening, it had not named a root cause or given a time for full recovery.

A Teams Fault and Wider Outage

Microsoft's status account first flagged users in North America who had issues accessing or using Teams on Thursday morning, US time. Microsoft said fixes restored the service and declared the impact fully resolved at 5:09pm UK time (12:09pm ET), though some users kept reporting connection problems. About 45 minutes later, it posted on X that users in the Americas were having trouble reaching their Exchange Online mailboxes via several connection methods, as shown below.

Some Teams features that rely on Exchange Online were also affected. Microsoft opened a wider advisory, MO1550821, listing Teams, Microsoft 365 Copilot, SharePoint Online, and Microsoft Defender XDR among services that could be affected. Downdetector recorded up to about 4,500 Teams reports, while Microsoft 365 reports peaked above 47,000. OpenAI and Anthropic both said Microsoft connectors inside their AI tools had problems, with some new connections possibly broken. Microsoft's own status page also appeared unreachable for some users.

The Cause

Microsoft first cited elevated load across multiple regions. Later it blamed offline servers, not extra traffic. These were failing automated health checks, possibly because of a component that processes them. 'We're aggressively pursuing all pathways to reduce impact,' Microsoft said, adding that it had paused all deployments, was moving traffic and restarting affected servers.

Shortly before 9pm UK time, a new health check method brought some servers back online, Microsoft said. Microsoft was widening the fix and preparing automated restarts for unresponsive servers. Microsoft found no recent change clearly linked to the outage's start, but was examining a few configuration updates as possible contributors.

By Friday morning, the incident remained unresolved, with no root cause or recovery time. Microsoft said there was no indication of malicious activity.

What Happens Next

Administrators can track the mail failure under incident EX1550543 in the Microsoft 365 admin centre. Microsoft also offered a public status page for admins locked out of it. A fuller explanation usually follows in a post-incident report. Downdetector figures count user complaints rather than confirmed failures, so the true number of people affected is unknown.

Public bodies were among those hit. The State of Michigan warned that replies to its emails could be delayed because of the wider outage. A 22 January outage also affected Outlook and Teams, while a Microsoft 365 outage from 31 August to 3 September stemmed from a fault in a core authentication configuration.