[German]Microsoft started rolling out the new Outlook app in Microsoft 365 a few days ago. There is also a support article regarding changes to deactivating the new Outlook app.
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Rollout of the new Outlook app
I announced in various articles here in the blog that Microsoft is gradually starting to migrate Outlook Classic to the new Outlook app (see e.g. Migration from Outlook Classic to New Outlook starts for business customers at the beginning of 2025).
Now neowin.net has noticed that Microsoft has started the rollout for Microsoft 365 and mentioned that in its support article Install new Outlook with a new Microsoft 365 deployment. Microsoft writes that starting with version 2502, new deployments of Microsoft 365 desktop client applications on Windows devices will include the new Outlook app by default. Administrators can choose whether they want to exclude the classic or the new Outlook or install both side by side.
New Outlook app: Changes for activation/deactivation
On March 27, 2025, Microsoft published the article MC922623 – Microsoft new Outlook for Windows and Outlook for the web: Changing how to disable/enable, which deals with changes to the activation/deactivation of the new Outlook app
It states that Microsoft is changing how to enable/disable the new Outlook for Windows and Outlook for the web. The rollout will start at the end of April 2025 (was once planned for February 2025) and will be completed by mid-May 2025.
Microsoft is changing the CASMailbox -OWAEnabled parameter, which enables or disables access to user mailboxes with Outlook for the Web (formerly known as Outlook Web App or OWA), to block only Outlook for the Web and not affect the behavior of the new Outlook for Windows.
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Administrators can manage new Outlook for Windows with the CASMailbox-OneWinNativeOutlookEnabled policy. To summarize: The CASMailbox-'OWAEnabled' parameter will only block Outlook for the Web, while the policy
CASMailbox-'OneWinNativeOutlookEnabled'
will manage the new Outlook for Windows. No administrative action is required before the rollout.
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