Microsoft announced Thursday that it is working to fix technical issues disrupting the sending and receiving of emails in its Outlook app.

The outage occurred during U.S. business hours, prompting users to report the problem on social media as schools, government agencies, and businesses were affected.

Outlook is a key component of Microsoft 365 productivity suites.
At 2:37 p.m. ET, Microsoft posted on X that it was investigating the issue impacting Outlook.

“Users may be receiving a ’451 4.3.2 temporary server issue’ error message when attempting to send or receive email through Outlook,” Microsoft said in an update.

Microsoft also warned that searches in OneDrive, Teams, and SharePoint Online could be slow or fail entirely. Users might be unable to create chats, meetings, teams, channels, breakout rooms, or live events in Teams, the company noted on its service dashboard.

In an X post at 3:17 p.m. ET, Microsoft said it had identified that “a portion of service infrastructure in North America” was not handling traffic correctly and that efforts were underway to resolve the issue.