Microsoft is updating how administrators enable or disable the Outlook (new) experience for Windows and Outlook on the web. This change allows IT administrators to independently enable or disable each Outlook, at last addressing long-standing confusion.
Originally set for rollout in late January 2025, the change is now scheduled to begin in late June 2025, with completion expected by mid-July 2025.
Now the CASMailbox –OWAEnabled enable/disable policy setting, despite the name, applies to both Outlook on the web (aka Outlook Web Access – OWA) and Outlook (new) for Windows.
When the changes are applied:
CASMailbox –OWAEnabled will only apply to Outlook on the web.
CASMailbox -OneWinNativeOutlookEnabled policy parameters are used to control access to the New Outlook.
After the changeover, only the OneWinNativeOutlookEnabled parameter will be checked.
Microsoft explains:
“ We will not change any existing value for the settings, but we will change which setting controls if the new Outlook for Windows is allowed for the user. Before this rollout, both CASMailbox-
OWAEnabledand CASMailboxOneWinNativeOutlookEnabledpolicies are checked. After this rollout, we will remove the check for CASMailbox-OWAEnabledso you can have the chance to enable new Outlook and still disable Outlook for the web if desired. “
This adjustment allows organizations, at last, to manage access to the New Outlook for Windows independently from Outlook on the web.
Why only now?
Why Outlook (new) didn’t have its own separate policy control from the start? It’s not like the replacement Outlook has arrived in the proverbial “last rainstorm”.
Most likely it was a trick to get Outlook (new) pushed out to organizations by combining the policy control with Outlook in a browser. Admins would enable –OWAEnabled thinking, understandably, that it allow only web Outlook, as the name suggests.
It’s just another in the long list of Microsoft trickery to get Outlook (new) onto computers whether it’s wanted or ready.
Administrators can find more details about this update in the Microsoft 365 Admin Center under message ID MC922623.
