A user asked about an article he saw in an online tech magazine, where the article said “classic Outlook is scheduled to go out of service by the end of April 2026.”
The user went on to add “I don’t think I’ll ever be ready to ditch Outlook, especially for an on-line version! “
First, classic Outlook is going to be with us and supported, with at least security updates, until 2029, if not longer. I’m hoping longer... I need VBA and PowerShell support. (When they remove classic Outlook from the subscription, I'll switch to a perpetual version.)
Microsoft really wants to push users into new Outlook (even though right now, the haters outnumber the people who like it) so they are changing from opt-in (you decide if you want to try new Outlook) to opt-out, where Microsoft switches you to new Outlook and you decide if you want to switch back.
Secondly, while I am not a fan of new Outlook, especially for users who do not use outlook.com or Microsoft 365 business mailboxes, new Outlook is not “an online version”. It is a desktop app that uses the same scripts as Outlook on the web, but with a current maximum of 180 days of mail cached locally if you are disconnected from the internet. (Offline options are in View tab > View Settings > General > Offline. Settings are per-account.)
In 2025 for Business Standard and in 2026 for Enterprise licenses, Microsoft will be switching new Outlook on for users. They will still be able to switch back to classic. Prior to being switched to new Outlook, users will receive warnings via in-app notifications.
From the Microsoft article Switch to new Outlook for Windows it is explained like this:
Small and Medium Businesses
Starting January 2025 and over the following months, if you are a classic Outlook user on the Current Channel with a Business plan, you will automatically be switched to the new Outlook after receiving a series of in-app notifications. You can choose to switch back to classic Outlook at any time, using the toggle in new Outlook. Both users and IT Admins can also turn off the automatic switch if not ready to try the new Outlook.
Users will not be switched to new Outlook if one or more of the following is true:
- New Outlook toggle is hidden via policy
- Perpetual license is in use
- If using an account not supported in new Outlook (only an on-prem Exchange mailbox currently)
- Admin set a policy blocking it
To hide the new Outlook toggle (item 1): See Use Classic Outlook, not New Outlook for the registry key you need to set. (I have a ready-to-use reg file available in the article.)
Information on the policy to block the switch (item 4) is in this article: Control the installation and use of new Outlook
You can use both classic Outlook and new Outlook, including at the same time. (I often have both open.) Switch on Try new Outlook, set up the accounts and pin new Outlook to the taskbar. Then toggle off New Outlook and restart classic Outlook. If the toggle is missing in the upper right of the app, look on the Help tab for the “Go to classic Outlook” button.
Because the icons are both blue with a white O, you probably won't want them to be side-by-side on the taskbar. (Classic Outlook is on the left, new Outlook on the right.)
Who should not switch to new Outlook?
Anyone using COM add-ins or VBA (or PowerShell) to extend or automate classic Outlook. Anyone using custom views or client-side rules.
For POP and IMAP accounts, my main issue is that the new Outlook pulls your mail into the Microsoft Cloud then syncs it to new Outlook rather than connecting the app directly to the mailbox. Offline caching is limited to up to 180 days of messages.
The "Microsoft Cloud" is what allows it to sync calendar and contacts from Gmail, Yahoo, and iCloud. If you use those accounts and want the calendar and contacts to sync, definitely try new Outlook. (The Outlook mobile apps work the same way - syncing your mailbox to the Microsoft cloud, which syncs with the app.)
Tip: When you remove an account from new Outlook and are asked if you want to remove it from all devices, selecting Yes will delete the mailbox from the cloud server. If you are using new Outlook on other computers or the Outlook mobile app, the account won't be automatically deleted from the devices but will stop syncing. You need to remove the account from the other devices manually.
Message Center articles for admins
Microsoft published articles for administrators in the message center:
For admins with Business Standard in the tenant: Toggle to new Outlook
Summary
Starting January 6, 2025, Microsoft 365 Business Standard and Premium users will be switched from classic to new Outlook for Windows. Users can revert to classic Outlook and provide feedback. The rollout requires no admin action but can be managed through a new policy.
Tenants with Enterprise subscriptions will have a message at Toggle to new Outlook
Summary
Starting April 2026, Microsoft 365 for Enterprise users will be switched from classic to new Outlook for Windows, with the option to revert back. This change aims to enhance user experience with modern features. Organizations are notified to prepare, with automatic rollout requiring no admin action but allowing opt-out options.
Thank you for the concise, informative, pertinent and timely article. There is hope for the Internet.