To switch back to the old (classic) Outlook from the new Outlook interface, you can follow these steps:

1. Use the Toggle in New Outlook (Windows):
   • Open Outlook.
   • At the top right corner, look for the toggle labeled New Outlook.
   • Switch this toggle off to revert to the classic Outlook.
   • You may be prompted to provide feedback or skip it. After that, the classic Outlook will open

2. If the Toggle Is Missing (Windows):
   • Launch classic Outlook from the Windows Start Menu by selecting the Outlook icon without the "New" tag.
   • If classic Outlook still opens the new interface, modify the Windows Registry:

     • Open Registry Editor (search for "Registry Editor" in Start Menu).

     • Navigate to:
       HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Preferences

     • Find the DWORD entry named UseNewOutlook.

     • Set its value to 0 to disable the new Outlook interface.

     • Close Registry Editor and try launching classic Outlook again from the Start Menu

3. On Mac:
   • Open Outlook.
   • Click the Outlook menu at the top.
   • Uncheck the option New Outlook.
   • Click the Revert button to switch back to the classic view

4. Additional Tips:
   • If you cannot find the toggle or the option to revert, ensure you are not launching the new Outlook app (which is often marked with a "New" tag).
   • You can also pin the classic Outlook to your taskbar for easier access

These methods allow you to switch back to the old Outlook interface if you find the new version lacking certain features or prefer the classic UI