Microsoft has begun rolling out a "Classic Outlook" theme for users of Outlook on the web and the New Outlook for Windows, aiming to provide a more familiar experience for those transitioning from older versions. This targeted release commenced in mid-August and is projected to be fully deployed by the end of September. Global general availability is anticipated between late September and late October.
The new theme introduces coordinated changes across the Outlook interface, encompassing visual styling, layout, typography, icons, and specific interactions. Microsoft stated that this update will not override existing administrator configurations and will not automatically migrate users from classic Outlook to the new client.
For most users, the Classic Outlook theme will be off by default, but it can be toggled on or off at any time via the "Settings > General > Appearance" menu. However, as part of a phased rollout, Microsoft will enable this setting by default for some users who are moving from classic Outlook to the new Outlook, though they retain the ability to change it.
The New Outlook for Windows, also referred to as Outlook for Windows, has been replacing Windows Mail as a pre-installed application. This transition occurred in October 2023 for Windows 11 and in January 2025 for other Windows versions. The first preview of the New Outlook client was released in May 2022.
The application reached general availability for personal accounts in September 2023, coinciding with the September 26 Windows fall update and availability through the Microsoft Store on Windows 11. For commercial customers, general availability was achieved in August 2024.
Despite reporting strong and accelerating adoption, Microsoft announced in February that it would postpone the opt-out phase for businesses from the New Outlook client, extending it from April 2026 to March 2027. This provides enterprise administrators an additional 12 months to prepare for a staged migration.
In a separate development, Microsoft also indicated in July its intention to disable Outlook Web Access (OWA) Light, a lightweight version of the Outlook Web App email client that was introduced approximately two decades ago as an alternative to OWA Premium. This change is expected to be implemented in a future Exchange Server update.
