how do i switch to classic outlook?

The biggest difference under Windows is that the classic Outlook has a File tab on the ribbon:

The File tab does not exist in the new Outlook or in the web version. (Outlook for Mac does not have it either.)

Yes, I can start "classic" or "new", but they pretty much look the same to me. Neither has the previous 2016 version classic look.

This option no longer exists on the latest Outlook 2021: >>>Uncheck the option for the New Outlook.

This registry option no longer exists either: >>>double-click on "UseNewOutlook"

Other suggestions?

Feedback was incorrectly clicked for 1 star. This did answer the question. 5 stars.

I hope you're doing well.

I've been exploring the registry to revert to the classic view in Outlook, but it seems that the "Preferences" folder is missing in the path \HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Preferences. Only "Resiliency" is listed.

I'm particularly keen to return to the classic view because it managed my add-ins like HubSpot more efficiently. Additionally, the classic view consistently applied to every email, and my email templates worked much better in that version and applied the correct contacts and signatures to each email. With HubSpot, I found it was always up or readily accessible, and my templates had more functionality, especially with Tables and photo insertion.

Thank you for your assistance.

Best regards,

Leemon