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Microsoft has confirmed that Microsoft Outlook is down for users worldwide on Monday, April 27, 2026. The outage began in the early morning hours and has prevented millions from signing into their email accounts. The company attributed the disruption to a “recently introduced change” that triggered widespread authentication failures.
Engineers began testing a potential fix by early afternoon Eastern Time. Full service restoration has not yet been confirmed. For the most up‑to‑date information, check the official Microsoft 365 Status account on X or visit Downdetector.
What Caused the Microsoft Outlook Outage?
Microsoft’s official statement points to a “recently introduced change” as the root cause. This change appears to have broken the identity verification layer that sits between a user and their inbox. The authentication servers began failing in a sudden wave, presenting “Account Not Authenticated” errors.
This incident follows a frustrating pattern. Earlier in April, a major outage took down Teams, Outlook, and Azure simultaneously. On April 22, another widespread disruption affected multiple Microsoft 365 services. For a complete timeline of all 2026 incidents, see our Microsoft 365 outage history .
Troubleshooting Steps to Try
While the outage is widespread, you can rule out local issues with these quick checks. If you see “Account Not Authenticated,” your best course is to wait. Repeatedly attempting to sign in does not help.
Try accessing Outlook from a different device or network. Sometimes, cached credentials on a specific device can cause a problem that looks like an outage. Mobile users who have been unexpectedly signed out should not uninstall the application, as this will not resolve a server‑side issue. Instead, monitor Microsoft’s official status page .
For a complete guide to solving common sign‑in errors—both during outages and on normal days—see our Outlook sign‑in error fixes . For workarounds you can use while Outlook is unavailable, read our alternatives to Outlook during downtime .
What to Do While Outlook Is Down
If your account is affected, email may be delayed even after the outage resolves. Avoid sending critical messages until Microsoft confirms service restoration.
Consider using alternative email clients or web‑based services to maintain communication. Many organizations also have backup communication tools such as Teams, Slack, or Zoom. Our workarounds guide for Outlook outages covers these options in detail.
How to Check If Outlook Is Back Online
Bookmark the official Microsoft 365 Service Health page . This is the single most reliable source. Downdetector provides real‑time user reports that often surface issues before official confirmations. For a detailed walkthrough on verifying outages, see our guide to checking Outlook status .
