How to Disable the new Outlook for Windows

There are several reasons why your organization might prefer not to adopt the new Outlook for Windows client. As Microsoft transitions to actively promoting the new Outlook client with an opt-out approach (rather than opt-in), it’s important to understand the options available.

This article explores the steps administrators can take to prevent the update to the new Outlook for Windows.

Step 1. Disable the toggle client-side

The following article services as the reference, prevent users from switching to new Outlook.

For Microsoft 365 administrators

You can hide the New Outlook option by configuring a cloud policy in the Microsoft 365 Apps admin center. To set up this policy:

Sign in to the Microsoft 365 Apps admin center.
Navigate to Customization and select Policy Management.
Click Create to set up a new cloud policy.
Search for the policy "Hide the 'Try the new Outlook' toggle in Outlook" and enable it.

For regular users

Push the following registry entry.

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Options\General]
"HideNewOutlookToggle"=dword:00000000

Step 2. Delaying the migration

The following article services as the reference, providing insights on the migration client-side.

Microsoft actively attempts to migrate the end-user towards the new Outlook for Windows experience. A system administrator however can disable these attempts.

To implement this change, the following GPO (registry entries) must be applied on the client side. The DWORD value for DoNewOutlookAutoMigration must be set to 0, which should effectively disable the migration to the New Outlook for Windows. To address any residual pop-ups that might still appear, it is recommended to additionally configure NewOutlookAutoMigrationRetryIntervals and set its value to 0 as well.

Notice: Currently, not setting NewOutlookAutoMigrationRetryIntervals has the same effect as setting it to 0. However, we explicitly configure this value to ensure the policy remains effective, even if the default behavior changes in the future.

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Options\General]
“DoNewOutlookAutoMigration”= dword:00000000

[HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Options\General]
“NewOutlookAutoMigrationRetryIntervals”: dword:00000000

Step 3. Disable the new Outlook for a mailbox

The following article serves as the reference, providing additional customization insights from Microsoft.

In the step outlined below, we will explain what actions the Exchange Administrator needs to take to disable authentication for the New Outlook for Windows against users mailboxes. For these steps we use Powershell extension for Exchange, here you can read more on configuring it.

The following command will disable mailbox access for the New Outlook for Windows across all users within the organization.

Disabling the new Outlook for Windows

Get-OwaMailboxPolicy | Set-OwaMailboxPolicy -OneWinNativeOutlookEnabled $false

Re-enable the new Outlook for Windows

Get-OwaMailboxPolicy | Set-OwaMailboxPolicy -OneWinNativeOutlookEnabled $true

Optional. Stopping 'New Outlook' from being installed on Windows 10 and 11

The following article services as the reference, control the installation and use of new Outlook.

By default, with the latest updates for Windows 10 and 11 (after 23H2), Microsoft is actively promoting the new Outlook client as part of the process of deprecating the older Mail and Calendar apps.

Windows 11

To remove the new Outlook for Windows installation, you can run the following powershell command.

Remove-AppxProvisionedPackage -AllUsers -Online -PackageName (Get-AppxPackage Microsoft.OutlookForWindows).PackageFullName

Lastly, remove the Windows orchestrator registry value at:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsUpdate\Orchestrator\UScheduler_Oobe\OutlookUpdate

Windows 10

In case Windows 10 is in the picture.

Remove the new Outlook for Windows installation first with powershell:

Remove-AppxProvisionedPackage -AllUsers -Online -PackageName (Get-AppxPackage Microsoft.OutlookForWindows).PackageFullName

Add the following registry key, this will prevent Windows updates from reinstalling the new Outlook for Windows.

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsUpdate\Orchestrator\UScheduler_Oobe\OutlookUpdate

Here you assign REG_SZ named BlockedOobeUpdaters with the value ["MS_Outlook"] (including brackets).