Microsoft doesn't really want customers to use the leaked Outlook client yet

A screenshot showing the interface of the leaked Project Monarch Outlook client

Although the upcoming web-powered Outlook client (Project Monarch) has been available for some months now, people who downloaded it were only recently able to sign into the application with their work and education accounts; personal accounts are still out of luck. That said, Microsoft has now published an advisory for customers who want to restrict access to the leaked version.

As noted by Tero Alhonen on Twitter, a new message (ID MC376710) on the Microsoft 365 admin center asks customers to wait for the officially released version and also provides some guidance about how admins can restrict access. The full message reads:

We are aware that some users can access an unsupported early test version of the new Outlook for Windows. This version is missing some of the features and enhancements that will be available later for our customers in the Beta Channel. We encourage our customers to wait for the beta version to be released.

We recognize the need for tenants to control access to apps in their organizations, so we are releasing early the instructions to do so. We expect to provide more news in the coming weeks about our Beta release. If you would like to block your users from connecting their Microsoft 365 accounts associated with your organization to this new app, please follow the PowerShell instructions. When the beta is available you will need to unblock them using the same instructions.

These instructions prevent the account from syncing to the new Outlook but do not prevent download.

NOTE: Our draft editor has an error where content between angular brackets does not display. As such, we have stricken our instructions below. Head over to message ID MC376710 in the Microsoft 365 admin center to view the PowerShell commands.

The instructions for different types of uninstalls are also described below:

To enable/disable access for a single user

Run the PowerShell app as an administrator
Input: Connect-ExchangeOnline -UserPrincipalName
Input: set-CASMailbox -OneWinNativeOutlookEnabled if enabling or if disabling

To enable/disable access for your entire organization

Run the PowerShell app as an administrator
Input: Connect-ExchangeOnline -UserPrincipalName
Input: Get-CASMailbox|Set-CASMailbox -OneWinNativeOutlookEnabled if enabling or if disabling

Of course, it makes sense that Microsoft does not want customers to use leaked applications in an enterprise environment. That said, it's also interesting to see references to more features being enabled in the client once it becomes officially available in the Beta Channel. We expect to hear more information on this front at Microsoft's Build conference later this month.

Via: Tero Alhonen (Twitter)