Microsoft asks iPhone users to reauthenticate after Outlook outage

Outlook Outage and iPhone Reauthentication: Detailed Post

Overview

• An outage affecting Outlook.com sign-ins led Microsoft to request iPhone users reauthenticate to access their Mail app accounts.
• The issue manifested as intermittent sign-in failures and, for some users, sign-out events accompanied by “too many requests” errors.
• Microsoft attributed the initial sign-in problems to a recently introduced change, but in-depth root-cause details were not disclosed.

What happened and timeline

• Outage onset: Monday, April 27, 2026, with users worldwide reporting sign-in problems when accessing Outlook.com services via the web and related clients.
• Microsoft confirmation: The company acknowledged the widespread sign-in failures and noted that some users were signed out mid-session and faced repeated request errors.
• Service update: By around 7:00 PM UTC on April 27, 2026, Microsoft stated that Outlook.com service health had returned to normal, but iOS users were instructed to re-enter credentials for the default Mail app access.
• Post-outage guidance: Microsoft advised iPhone users to complete a manual reauthentication process to restore mailbox syncing through the built-in Mail app.

Impact and scope

• Affected platform: Primarily customers using the iPhone Mail app to access Outlook.com and Hotmail accounts.
• Access mode: Sign-ins via the default Mail app were the focus, though Outlook.com access issues were reported across multiple endpoints (web, desktop, and Exchange protocols) in related incidents.
• Regional and user counts: Microsoft did not publish specific regional impact data or the total number of affected users for this outage.
• Incident classification: The event was described as a service degradation with noticeable user impact rather than a complete global outage.

iPhone reauthentication steps (step-by-step)

• Purpose: To restore access to Outlook and Hotmail accounts via the iPhone’s Mail app after the outage.1) Open the Settings app on your iPhone.2) Scroll down and tap on Mail.3) Select Accounts under the Mail settings.4) Tap on the email account for which you need to re-enter the password.5) Tap Account Settings or the Password field directly (depending on your iOS version).6) Enter the updated or correct password in the Password field.7) Tap Done to save the changes.8) Open the Mail app to confirm that the account is syncing properly and emails are being sent/received.

Additional context and related issues

• Prior incidents at a Glance:
• March: Microsoft faced an Exchange Online outage that restricted access to mailboxes and calendars via multiple clients and protocols.
• The same day: A separate issue was resolved that affected sign-ins for Microsoft 365 Copilot and related services across Copilot desktop apps, Teams Copilot, and Office apps.
• Early April: A known issue prevented some Classic Outlook users from sending or replying to emails via Outlook.com, with non-delivery reports (NDRs) containing specific error codes.
• Ongoing investigations:
• A separate bug affecting the mouse pointer visibility for some Classic Outlook, OneNote, and other Microsoft 365 apps was being investigated.
• Another issue surfaced involving “Can’t connect to the server” errors when creating groups in Classic Outlook.

Current status and what’s known

• Service health: Microsoft reported that the Outlook.com service had returned to normal as of the stated update, but required user-initiated credential reentries on iOS devices to recommence normal mailbox syncing.
• Root cause: No detailed post-outage root-cause disclosure was provided publicly in the update.
• User guidance: The official procedure for iPhone users to reauthenticate is provided above; no additional remediation steps were publicly listed beyond credential re-entry.

Notes on the broader Outlook ecosystem

• Outlook.com continues to experience a history of related outages and intermittent issues across Exchange Online, Copilot integrations, and classic client experiences.
• Microsoft remains active in monitoring and addressing sign-in, synchronization, and server-connection issues across multiple platforms and devices.

Summary

• A recent Microsoft outage prompted iPhone users to reauthenticate their Outlook and Hotmail accounts in the built-in Mail app.
• The service reportedly stabilized, but a manual credential refresh was required for iOS users to regain full mailbox syncing.
• The event sits within a broader pattern of Exchange Online and Outlook-related incidents, and Microsoft continues to investigate root causes while guiding users through known reauthentication steps.