Microsoft is also migrating corporate customers to new Outlook - from April 2026

Microsoft also wants to migrate customers with Enterprise licenses to the new Outlook. From 2026, the classic Outlook clients with local data processing will also be replaced by the "new Outlook" web app in this environment. However, admins should be able to prevent this.

The company posted a corresponding notification in the Microsoft 365 Admin Center at the weekend (account with sufficient permissions required for access). "Starting in April 2026, Microsoft 365 Enterprise customers will be transitioned from classic to new Outlook, with the option to revert," Microsoft writes there. "This change aims to enhance the user experience with modern features. Organizations will be notified to prepare, with automatic deployment requiring no action on the part of admins, but offering opt-out options."

New Outlook: distribution schedule in place

In the first round, users will be switched to the new Outlook once, Microsoft explains. However, those affected will have the opportunity to switch back and use classic Outlook. However, further attempts to switch over could be made in the future. "The new Outlook offers users a modern experience with co-pilot functions, visual adjustments and a range of time-saving functions such as pinning and deferring emails," says Microsoft to make the switch appealing.

"Users will receive a notification in the app before they are switched," Microsoft explains further. This can be reversed in the Outlook settings under 'General'. "Anyone who has been automatically switched to the new Outlook can switch back to classic Outlook," the provider emphasizes. The changeover will not take place if admins have exempted their users from it by means of "Admin control over migration" or have hidden the changeover to the new Outlook by means of a policy, use a perpetual license or use on-premises access.

New Outlook may be problematic

The new Outlook relies on server-side mail processing and therefore collects all emails in Microsoft's cloud. The new Outlook transfers IMAP access data to Microsoft servers, for example, which then collect emails from there. The new functions, such as AI support, rely on server-side computing power. This can be undesirable, especially in a corporate environment. Another frequent problem is that the new Outlook cannot handle local mailbox files, such as .pst files.

At the beginning of November, Microsoft announced that customers with "smaller" business licenses than the Enterprise versions would be forced to switch to the new Outlook. However, this will start in just under a month, on January 6, 2025, and Microsoft also explained ways for admins to prevent this switch in their networks.

(dmk)