Find notable cyber news and cases, enriched with sources, timelines, and signals.
Home Watchlists Beta Browse News Feed Stats About Contact

Microsoft Exchange Online service disruption causing authentication and email failures

Service Disruption
First reported
Last updated
Happening score
H score 0
1 unique sources, 1 articles

Summary

Hide ▲

Microsoft is investigating a widespread Exchange Online outage that is disrupting authentication and email delivery for tens of thousands of users. The issue is affecting message sending and receiving, mailbox operations, and access to Exchange Online and Outlook. Microsoft says it has isolated a common failure pattern and is working on remediation options.

Related Happenings

Microsoft 365 apps search disruption

Service Disruption
H score0 First: 18.08.2026 12:24 Last: 18.08.2026 12:24 Sources 1

About this happening: Microsoft is facing a search disruption in Microsoft 365 apps that is preventing some users from finding content in SharePoint Online, OneDrive, Outlook on the w...

Open Happening

Microsoft Azure and Microsoft 365 outage caused by maintenance bug

Service Disruption
H score0 First: 24.07.2026 18:41 Last: 24.07.2026 18:41 Sources 1

About this happening: A maintenance-system bug triggered a massive Microsoft outage that disrupted access to Azure and Microsoft 365 services for customers tied to West US infrastru...

Open Happening

Microsoft Exchange Online mailbox quarantine disruption after infrastructure change

Service Disruption
H score0 First: 23.07.2026 12:20 Last: 23.07.2026 12:20 Sources 1

About this happening: A Microsoft Exchange Online service disruption is mistakenly quarantining customer mailboxes, blocking email delivery and calendar access for affected users. The issue...

Open Happening

Microsoft security patch release for CVE-2026-45586

Security Patch Release
H score41 First: 09.06.2026 20:57 Last: 09.06.2026 20:57 Sources 1

About this happening: Microsoft's June 2026 Patch Tuesday delivers 200 flaw fixes across Windows and related products, including six zero-days and one actively exploited vulnerability....

Open Happening

Microsoft Exchange Online mail flow disruption

Service Disruption
H score25 First: 02.06.2026 20:02 Last: 02.06.2026 20:02 Sources 1

About this happening: Microsoft is addressing a widespread Exchange Online service disruption that is delaying and failing email delivery for customers across North America and Germany. The...

Open Happening

Timeline

  1. 31.08.2026 20:30 2 articles · 0h ago

    Microsoft investigates Exchange Online outage causing authentication and email failures

    Initial Disclosure

    Microsoft began investigating a widespread Exchange Online service issue after a stream of user reports on social media and a Downdetector spike indicated tens of thousands of affected users. The disruption is causing authentication-related errors, delays or failures when sending and receiving email, mailbox-operation problems, and access issues in Exchange administration experiences.

    Show sources
    Open in new tab