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Microsoft Outlook and Exchange Online suffer global outage
A massive global outage affecting Microsoft Outlook and Exchange Online disrupted email services for millions of users on August 31, 2026. The incident, tracked as EX1464935, caused widespread issues including login failures, difficulties sending or receiving emails, mailbox synchronization errors, and application freezing.
Microsoft identified the root cause as a technical error within a central authentication and connectivity component of the Exchange Online cloud infrastructure. The disruption also impacted other Microsoft 365 services, including Teams, OneDrive for Business, SharePoint Online, Microsoft Purview, and Microsoft Defender XDR.
Downdetector reported tens of thousands of user complaints during the peak of the outage. Microsoft has since initiated remediation efforts, rolling out updates to affected servers to restore services. While telemetry data indicates a gradual recovery and systems are beginning to stabilize, some users may still experience delays in email delivery and mailbox synchronization as backlogs are processed.
Entities
Downdetector · Exchange Online · Microsoft · Microsoft 365 · Microsoft Outlook · Outlook
Claims
What the coverage asserts, and how many sources carry each claim.
- [● 11 SOURCES] Users reported issues including failure to send or receive emails and the Outlook app freezing. www.tomsguide.com · www.allgaeuer-zeitung.de · ourdailynewsonline.com · sea.mashable.com · techxeber.az · +6 more
- [● 31 SOURCES] The incident has been logged in the Microsoft 365 admin center as EX1464935. cybersecuritynews.com · www.tomsguide.com · www.allgaeuer-zeitung.de · ourdailynewsonline.com · www.focus.de · +22 more
- [● 8 SOURCES] Downdetector reported tens of thousands of user problems with Microsoft Outlook and Exchange Online. www.ibtimes.com.au · cybernoz.com · ourdailynewsonline.com · fenix-magazin.de · www.allgaeuer-zeitung.de · +3 more
- [● 5 SOURCES] Microsoft is investigating reports of issues with Exchange Online. cybersecuritynews.com · www.tomsguide.com · ourdailynewsonline.com · cybernoz.com
- [● 25 SOURCES] Microsoft identified the cause as an issue with an authentication component in the Exchange Online cloud infrastructure. www.allgaeuer-zeitung.de · au.lifehacker.com · sea.mashable.com · cybernoz.com · brandaktuell.at · +19 more
- [● 19 SOURCES] Microsoft has developed a remediation strategy and is testing it on a portion of its infrastructure. au.lifehacker.com · sea.mashable.com · www.allgaeuer-zeitung.de · www.focus.de · brandaktuell.at · +12 more
- [● 7 SOURCES] Users reported that mailboxes were failing to synchronize. www.allgaeuer-zeitung.de · www.focus.de · brandaktuell.at · fenix-magazin.de · techxeber.az · +1 more
- [● 5 SOURCES] Users reported significant difficulties with logging into their accounts. www.allgaeuer-zeitung.de · ourdailynewsonline.com · techxeber.az · cybernoz.com