Teams went down first, so nobody could complain about Outlook going down
July 2025 outage left Outlook mailboxes unreachable on web, desktop and mobile
The market's verdict: +0.4% on MSFT in the week after.
What actually happened
On July 10, 2025, Microsoft 365 spent the day apologizing: first Teams meetings stopped loading, then Outlook mailboxes became unreachable from the web, the desktop apps and phones, all of them at once. Microsoft's status updates explained that a portion of mailbox infrastructure was not performing as efficiently as expected, which is one way to describe mail not arriving. Service was restored by 4:41 in the afternoon, UTC. A generation of workers relearned the phone number of everyone they had ever met.
This one is officially acknowledged.
Links
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Acknowledgement
- Microsoft Q&A (official)
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Impact
- Neowin (publication)
↳ caused by Mailbox infrastructure degradation (July 2025)
Timeline
- Jul 10, 2025 Confirmed First reports came in.
- Jul 10, 2025 Fixed Resolved at 16:41 UTC the same day.