The announcement of the Windows Mail app's deprecation has led to the automatic launch of the newer Outlook (new) application on many Windows 11/10 systems. For users who prefer the full-featured Outlook desktop client (Outlook (classic)), several methods exist to restore its default behavior.

Key Differences Between Outlook Versions

• Outlook (new): This free applictaion from the Microsoft Store replaces the legacy Mail app, offering an interface and experience identical to Outlook on the web.
• Outlook (classic): This is the traditional desktop application included with Microsoft 365 or Office suites, offering advanced features and deep integration with other Office applications. It requires a paid license.

Method 1: Disable the Toggle Switch in Outlook (new)

The simplest approach is to locate and turn off the "Try the new Outlook" toggle switch located in the top-right corner of the Outlook (new) application window. This action should allow the system to revert to launching the classic Outlook client.

Method 2: Modify the Windows Registry

If the toggle method is ineffective, editing the Windows Registry can force the system to use the classic version. Warning: Incorrect registry edits can cause system instability. It is highly recommended to create a system restore point before proceeding.

1. Open the Registry Editor (regedit).
2. Navigate to the following key:

   HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\Preferences
   

3. In the right pane, look for a DWORD value named UseNewOutlook. If it does not exist, right-click in the empty space, select New > DWORD (32-bit) Value, and name it UseNewOutlook.
4. Double-click the UseNewOutlook value and set its Value data to 0.
5. Click OK, close the Registry Editor, and restart your computer for the change to take effect.

Method 3: Uninstall the Outlook (new) Application

You can remove the new application from your system.

1. Open Settings > Apps > Installed apps.
2. Search for "Outlook".
3. Click the ellipsis (...) next to "Outlook (new)" and select Uninstall.

Method 4: Create a Desktop Shortcut for Outlook (classic)

If both applications are installed, Windows Search might prioritize the new version. Creating a direct shortcut to the classic executable ensures easy access.

1. Open File Explorer and navigate to the Microsoft Office installation directory. A common path is:

   C:\Program Files\Microsoft Office\root\Office16\
   

2. Locate the OUTLOOK.EXE file.
3. Right-click the file, select Show more options > Send to > Desktop (create shortcut). You can use this shortcut to launch the classic Outlook application directly.