Update 8/13/2026: This retirement is now complete, please see Released: August 2026 Exchange Server Security Updates | Microsoft Community Hub. For customers who do not have access to August 2026 Exchange security updates, we recommend that you disable OWA Light as per instructions below.
We are announcing our plan to retire and disable the OWA Light experience in Exchange Server in a future update. OWA Light was created for a much earlier era of the web, when browser support, bandwidth, and accessibility technologies were very different from today. Going forward, we want to invest in modern Outlook on the web experience that provides the cross-browser, accessible, and security-focused experience.
Organizations that still rely on OWA Light must move users to the standard Outlook on the web experience and review any internal guidance, bookmarks, training material, helpdesk scripts, or accessibility workflows that reference OWA Light.
This is how OWA Light looks like:
What is changing
In an upcoming Exchange Server update (estimated in August 2026), we plan to disable and remove the OWA Light experience. After that change is introduced, users will no longer be able to choose or be redirected to OWA Light and should use the modern Outlook on the web experience instead.
This announcement applies to Exchange Server (on-premises). We announced deprecation of OWA Light in August 2024.
Why we are making this change
OWA Light served customers well for many years. It was designed for older browsers, slower connections, and scenarios where a simplified web interface helped users access mail in environments that could not support the full Outlook Web App experience.
The web has changed significantly since OWA Light was introduced. Modern browsers are more capable and more consistent, network conditions have improved for many customers, and security landscape has changed significantly. Maintaining a separate legacy OWA Light experience increases complexity. Each additional content rendering path, control surface, and compatibility layer must be evaluated as we strengthen defenses against modern web threats.
We recommend that Exchange Server administrators use this time to identify and prepare any users, processes, or documentation that still depend on OWA Light.
To block OWA Light right away, you can create or update an existing OWA mailbox policy:
Set-OwaMailboxPolicy -OwaLightEnabled $falseMake sure that the OwaMailboxPolicy is assigned to all mailboxes. You can assign a OwaMailboxPolicy by using the Set-CasMailbox -OwaMailboxPolicy cmdlet.
Additionally, disable the OWA Light selection menu on the OWA logon page. You can do that by running:
Set-OwaVirtualDirectory -LogonPageLightSelectionEnabled $falseMore information can be found in the Set-OwaMailboxPolicy and Set-OwaVirtualDirectory documentation.
Summary
OWA Light was an important compatibility experience when the web needed it. Today, the full Outlook on the web experience is the right place for us to focus. Retiring OWA Light will help reduce legacy surface area, simplify ongoing engineering work, and allow us to continue improving the experience customers use every day.
The Exchange Server team
