The tech giant said it is investigating the incident.
Microsoft Exchange and Teams Calendar are currently down worldwide, with Outlook also “crashing,” according to users who said they could not view or send emails.
Microsoft did not specify the cause of the issues but said: “We’ve started to deploy a fix which is currently progressing through the affected environment”.
“While this progresses, we’re beginning manual restarts on a subset of machines that are in an unhealthy state” the company said six hours after reports emerged of Microsoft 365 being down.
Reports on Downdector, a website that tracks outages, started just before 8.40 am CET, reporting more than 800 reports from users that the services were not working.
When loading Outlook, an error page appears: “Your request can’t be completed right now”.
Why is it down?
Microsoft said that it had identified “a recent change which we believe has resulted in impact”. But it did not give any more details, nor specify an exact reason.
“We’ve started to revert the change and are investigating what additional actions are required to mitigate the issue,” the company said in a post on social media platform X on Monday morning.
Users also reported that Outlook was down.
“Has been acting up all morning, Exchange Online, Teams, Outlook, none of these services are working as expected, can’t get in to see quarantined emails either,” one user wrote on X.
Users from The Netherlands, Poland, France, and Sweden wrote on X that they were having issues with Microsoft’s Outlook.
According to the email marketing platform website, Mailmeteor, the services are affected worldwide.
“A service outage is currently affecting Microsoft Outlook. More than 423 reports were made today,” the website said.
This story is being updated by our journalists.