M365 Changelog: Some users can access an unsupported early test version of the new Outlook for Windows

MC376710 – Microsoft is 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. Microsoft encourages its customers to wait for the beta version to be released.

Microsoft recognizes the need for tenants to control access to apps in their organizations, so it’s releasing early the instructions to do so. Microsoft expects 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.

To enable/disable access for a single user:

1. Run the PowerShell app as an administrator
2. Input: Connect-ExchangeOnline -UserPrincipalName <administrator email>
3. Input: set-CASMailbox <Email being enabled/disabled> -OneWinNativeOutlookEnabled <$true> if enabling or <$false> if disabling

To confirm that this was successful:

Input: Get-CASMailbox <email being checked> | Select *

Scroll through the list of mail clients and confirm that OneWinNativeOutlookEnabled has the required value next to it

To enable/disable access for your entire organization:

1. Run the PowerShell app as an administrator
2. Input: Connect-ExchangeOnline -UserPrincipalName <administrator email>
3. Input: Get-CASMailbox|Set-CASMailbox -OneWinNativeOutlookEnabled <$true> if enabling or <false> if disabling

Additional information