Microsoft office building at RheinauArtOffice on September 11, 2025 in Cologne, Germany.
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microsoft announced Thursday that it is working to resolve a technical issue that is preventing users from sending and receiving email messages in the Outlook application.
The incident occurred during business hours in the US and prompted people to mention the disaster on social media as schools, government agencies and businesses dealt with the outage. This program represents a core part of the Microsoft 365 productivity software bundle.
At 2:37 p.m. ET, the company announced in an X post that it was investigating an issue affecting Outlook.
“Users may receive a ‘451 4.3.2 Temporary Server Problem’ error message when they try to send or receive email through Outlook,” Microsoft said in an update to its online dashboard.
Additionally, searches in the OneDrive cloud file storage application and SharePoint Online collaboration service may be slow or not work at all, the company said in its dashboard.
In an X post published at 3:17 p.m. ET, Microsoft said it discovered that “portions of its North American service infrastructure” were not handling traffic correctly and was working to fix the issue.
A follow-up post at 4:14 p.m. ET said the company had restored the affected infrastructure and was directing traffic to other infrastructure for recovery.
Last July, the Outlook outage lasted more than 21 hours.
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