The future of Microsoft's mail clients, Outlook Web It has been rumored for a long time that it will be similar to the app, and recent leaks show that One Outlook confirms that the new client, named , will be web-based.
One Outlook New Technologies
- OPX – OWA Powered Experiences: OPXis a method that allows other mail clients to use features developed for Outlook Web App (OWA). This technology works based on the WebView2 component developed by the Microsoft EDGE team. WebView2 is also considered the architectural key to the Teams 2.0 client.
- Microsoft SYNC Technology: Microsoft SYNC is a protocol that Outlook Mobile (iOS and Android) and Outlook for Mac clients use to interact with Exchange Online.

One Outlook Block Steps
Microsoft has shared new techniques for organizations that want to block the ONE Outlook app. You can simply use PowerShell to block the One Outlook app. This process is similar to how we block a mailbox from accessing a protocol like Exchange ActiveSync, “CasMailbox” can be done using the command set.
Block One Outlook App for a Single User
To block a specific user from accessing the One Outlook client, you can use the following command:
Set-CasMailbox -Identity Cengiz.Yilmaz -OneWinNativeOutlookEnabled $False
Block One Outlook App across the organization
If you want to block the One Outlook client throughout your organization, the following set of commands can be used:
Get-ExoMailbox -RecipientTypeDetails UserMailbox -ResultSize Unlimited | Set-CasMailbox -OneWinNativeOutlookEnabled $False
Unblock for One Outlook
If you want to allow One Outlook usage across your organization, you can use the following command.
Get-ExoMailbox -RecipientTypeDetails UserMailbox -ResultSize Unlimited | Set-CasMailbox -OneWinNativeOutlookEnabled $True