Disruptions appeared to peak just before noon ET on Thursday, when more than 2,700 users worldwide reported issues with Outlook, formerly also Hotmail, to outage tracker Downdetector. Some said they encountered problems like loading their inboxes or signing in.
By later in the afternoon, reports had fallen to just over a couple hundred. And in an update on social media shortly after 3:30 p.m. ET, Microsoft 365 said that a configuration change had "fully saturated throughout the affected environments and resolved impact for all users."
"Everything is up and running," Microsoft's status page added.
Microsoft did not immediately provide more information about what had caused the hourslong outage. A spokesperson for Microsoft had no further comment when reached by The Associated Press on Thursday.