Microsoft has started rolling out a Classic Outlook theme for users of Outlook on the web and the New Outlook for Windows.
This new Outlook theme is rolling out as part of a targeted release beginning mid-August and expected to complete by the end of September. The theme will become generally available worldwide between late September and late October.
“When enabled, the setting applies coordinated changes across the Outlook experience, including visual styling, layout, typography, icons, and selected interactions,” Microsoft said in a Microsoft 365 Message Center update.
Once rolled out, the feature will not override any existing administrator configurations and will not automatically migrate users from classic Outlook to the new Outlook.
Microsoft also added that the new user interface style will be enabled by default for some users, but they can toggle it off to switch to the standard theme from Settings > General > Appearance.
“This update is designed to help users who are transitioning from classic Outlook by providing a more familiar experience while maintaining the capabilities of the new Outlook,” it added.
“The setting will be available to all users and can be turned on or off at any time. It will be off by default for most users. As part of a phased rollout, Microsoft will enable the setting by default for some users moving from classic Outlook to the new Outlook. Those users can change the setting at any time.”
New Outlook (also known as Outlook for Windows), which still lacks some Classic Outlook features, replaced Windows Mail as a pre-installed app on Windows 11 and Windows starting in October 2023 and January 2025, respectively.
Microsoft introduced the first preview version of the New Outlook client in May 2022. The app reached general availability for personal accounts in September 2023 (via the September 26 Windows fall update and the Microsoft Store on Windows 11) and for commercial customers in August 2024.
In February, Microsoft announced that it would postpone the new Outlook opt-out phase for businesses from April 2026 to March 2027, giving enterprise admins 12 additional months to prepare a staged migration to the new client.
Microsoft made this decision even though, according to the company, it was “seeing strong and accelerating adoption of new Outlook.”
In July, Microsoft also said that it would disable Outlook Web Access (OWA) Light, a lightweight version of the Outlook Web App email client introduced roughly two decades ago as an alternative to OWA Premium, in a future Exchange Server update.
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