Microsoft is scrambling to restore its Microsoft 365 services after a major outage knocked out Outlook email for business users around the world. Teams, SharePoint and Copilot were also hit with Australian businesses facing serious disruptions.

The problems began early Friday morning Australian time (Thursday afternoon US Eastern time). Microsoft first said the issue was limited to Exchange Online mailboxes in the Americas, then admitted it “may affect Microsoft 365 service connectivity for users in any region.”

At the time of writing, Microsoft had not given a time for full restoration.

What Went Down

The outage centres on Exchange Online, the cloud mail platform behind Outlook for business and enterprise Microsoft 365 customers. Microsoft is tracking it as incident EX1550543.

Users reported being unable to reach mailboxes through Outlook on the web, the desktop and mobile apps, and the MAPI, ActiveSync and REST connection methods used by third-party mail clients. They also reported calendar failures and problems logging into Microsoft 365.

A second advisory, MO1550821, confirms customers may be unable to connect to Exchange Online, Microsoft Teams, SharePoint Online, Microsoft 365 Copilot and Microsoft Defender XDR. Microsoft says that incident began at 1.26pm ET (5.26am AEDT).

Consumer Outlook.com appears to have been largely unaffected. The damage fell mainly on paying business customers, which is where Microsoft makes its money.

Even the tools admins use to check on the outage were unreliable. Some IT managers could not get into the Microsoft 365 admin center, and Microsoft’s own status pages struggled to load.

The Numbers

Downdetector recorded close to 130,000 Outlook problem reports just after 1pm ET (5am AEDT). Tens of thousands more reports were logged against Microsoft 365, Teams, Copilot, Azure, OneDrive and the Microsoft Store.

The fallout reached government. The US state of Massachusetts told staff its email and other Microsoft services were unavailable.

Teams had a separate wobble earlier in the day in North America, tracked as TM1550488. Microsoft said that problem had been restored, though some users continued to report connection issues.

Microsoft’s Explanation

Microsoft initially blamed “elevated load across multiple regions” on part of its infrastructure.

It later clarified that the load was not caused by a surge in demand. A number of servers had become unexpectedly unavailable, leaving the remaining servers to carry the traffic.

Its latest update says it is testing a configuration change to fix a problem causing servers to fail automated health checks and drop out of service. It has also:

Paused all deployments
Redistributed connection traffic across its worldwide infrastructure
Moved additional traffic off the affected infrastructure
Started a restart of all affected servers, which it is monitoring as they come back online

“We’re aggressively pursuing all pathways to reduce impact,” the company posted on its Microsoft 365 Status account on X.

Australian Impact

Microsoft’s statement that users “in any region” may be affected puts Australian businesses in the firing line as they start the working day on Friday. That matters for retailers, resellers and distributors running sales and supply chains through Outlook and Teams.

Admins should check incident EX1550543 and MO1550821 in the Microsoft 365 admin center, or status.cloud.microsoft if the admin center won’t load. Resetting passwords or reconfiguring Outlook will not help while the fault is on Microsoft’s side.

Another One

This is the second major Microsoft 365 outage this year. On 22 January, Outlook, Teams and other 365 services were down for many hours before Microsoft declared the problem resolved.

The pattern is a familiar one. A huge share of global business runs on a handful of cloud platforms, and when one of them stumbles, the impact spreads across thousands of organisations at once.

ChannelNews has contacted Microsoft Australia for comment. We will update this story as services are restored.