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Microsoft Exchange Online mailbox access disruption

Service Disruption
First reported
Last updated
Happening score
H score 13
1 unique sources, 2 articles

Summary

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The Exchange Online service is undergoing an ongoing mailbox access disruption that can stop some users from opening cloud mailboxes through Outlook mobile and the new Outlook for Mac desktop client. Microsoft identified the cause as a newly introduced virtual account change and is reverting/disabling the change across affected environments. The issue has been present since Thursday and was still being investigated on Saturday. Microsoft has not disclosed affected regions or user counts, so the current scope remains unclear.

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Timeline

  1. 23.03.2026 14:17 1 articles · 2mo ago

    Exchange Online mailbox access disruption begins

    Initial Disclosure

    Microsoft Exchange Online users began experiencing intermittent mailbox access failures through Outlook mobile apps and the new Outlook for Mac desktop client starting Thursday, and Microsoft later tracked the service issue as EX1256020.

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  2. 23.03.2026 14:17 2 articles · 2mo ago

    Microsoft reverts the Exchange Online virtual account change

    Mitigation Patch Update

    After identifying a newly introduced virtual account change as the root cause of the Exchange Online access problem and failing to resolve it by restarting affected infrastructure, Microsoft began reverting and disabling the change across affected environments on Saturday.

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