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What’s Changing in Microsoft’s New Outlook App Rollout? Key Updates Explained
Microsoft has introduced the new Outlook app for Microsoft 365, marking a shift from the classic version. This rollout brings changes for administrators and users alike, particularly in how the app is activated or deactivated. Let’s break it down.
Rollout Details
- Starting with version 2502, the new Outlook app will be included by default in new Microsoft 365 desktop deployments on Windows devices.
- Administrators can choose between installing the classic Outlook, the new Outlook, or both versions side by side.
- The rollout began in late March 2025 and is set to complete by mid-May 2025.
Changes to Activation/Deactivation
Microsoft has updated how administrators manage access to Outlook for Windows and Outlook for the Web:
CASMailbox Parameter Updates
- The CASMailbox-OWAEnabled parameter now blocks only Outlook for the Web (formerly OWA). It no longer affects the new Outlook for Windows.
- This change ensures more granular control over web-based access without disrupting desktop client behavior.
New Policy for Windows Client
- The CASMailbox-OneWinNativeOutlookEnabled policy allows administrators to manage access specifically for the new Outlook app on Windows devices.
Key Takeaways for Administrators
No immediate action is required before this rollout.
- These updates simplify mailbox management by separating controls for web and desktop versions of Outlook.
- Administrators can now tailor their deployment strategies based on organizational needs without overlapping configurations.
This rollout is a significant step in modernizing Microsoft’s email client ecosystem while offering administrators better flexibility in managing user access. For businesses relying heavily on Microsoft 365, understanding these changes ensures smoother transitions and avoids disruptions.