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Microsoft Outlook Classic Bug Prevents Opening Encrypted Emails

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Last updated
1 unique sources, 2 articles

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A bug in Microsoft Outlook Classic prevented users from opening encrypted emails with 'Encrypt Only' permissions after a recent update. The issue affected recipients who tried to open these emails, displaying an error message and an inaccessible attachment instead of readable content. Microsoft has now released a fix for the Beta Channel and plans to roll it out to the Current Channel in February. Temporary workarounds include saving encrypted emails before sending, reverting to a previous software build, or using the Encrypt option under the Options ribbon.

Timeline

  1. 30.01.2026 16:48 1 articles · 23h ago

    Microsoft Releases Fix for Outlook Classic Encrypted Email Bug

    Microsoft has released a fix for the Outlook Classic bug that prevented opening encrypted emails. The fix is available in the Beta Channel and will roll out to the Current Channel in February. Additional temporary workarounds have been provided.

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  2. 07.01.2026 18:30 2 articles · 23d ago

    Microsoft Investigates Outlook Classic Bug Preventing Opening Encrypted Emails

    Microsoft has fixed the known issue that prevented Microsoft 365 customers from opening encrypted emails in classic Outlook after a December update. The fix is available for customers in the Beta Channel and will roll out to the Current Channel (Build 19725.20000) and Current Channel Preview (Build 19725.20000) in February. Temporary workarounds include using the Encrypt option under the Options ribbon or reverting to a previous software build.

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Information Snippets

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Windows 11 Update KB5074109 Causes Outlook Freezes for POP Users

Microsoft has released emergency out-of-band updates on January 25, 2026, to address an issue causing Microsoft Outlook to freeze for users with POP email accounts. The problem, which affects users of Windows 11 25H2 and 24H2, Windows 10, and multiple Windows Server platforms, occurs when PST files are stored in cloud storage like OneDrive or Dropbox. The issue prevents Outlook from exiting properly and restarting after being closed. Users can temporarily resolve the issue by uninstalling the KB5074109 update or accessing their email accounts via webmail or moving their Outlook PST files out of OneDrive. The out-of-band updates include fixes for other issues, such as access to Microsoft 365 Cloud PC sessions and Secure Launch bugs.

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Microsoft Outlook New Client Excel Attachment Opening Issue

Microsoft is addressing a known issue affecting the new Outlook client, preventing users from opening Excel attachments with non-ASCII characters in the file name. The bug, identified on November 23rd, triggers an error message prompting users to try opening the file again later. Microsoft has deployed a fix but it has not yet reached all affected users. The issue has been tagged as an advisory, indicating limited scope or impact. Users are advised to use Outlook on the web or download the file to open it locally.

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Microsoft 365 classic Outlook crashes on launch

Microsoft 365 customers using classic Outlook on Windows systems are experiencing crashes upon launch. The issue requires Exchange Online support intervention to mitigate. Users see an error message stating that Outlook cannot start and that logging into the Exchange account has failed. Microsoft is investigating the root cause and has provided a temporary workaround using the new Outlook for Windows or Outlook Web Access (OWA).

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Outlook encrypted email errors affecting cross-tenant communications

Microsoft is investigating an issue with Outlook that prevents users from opening encrypted emails sent from other organizations. The problem affects users of the classic Outlook email client across all Office channels. A temporary workaround is available, involving adjustments to cross-tenant access settings. The error occurs when attempting to open OMEv2 encrypted emails, resulting in a message stating 'Configuring your computer for Information Rights Management.' The issue impacts users who receive encrypted emails from external tenants. The workaround involves enabling cross-tenant access to trust MFA claims from other organizations, which allows encrypted emails to be opened without errors. However, both the sending and receiving organizations must apply this fix for it to work.

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