NewOutlook · Outlook on the Web · New Outlook for Windows
Outlook: Right-click to customize the classic ribbon
Users can now customize the classic ribbon in New Outlook for Windows and Outlook on the Web by right-clicking to select which commands and groups appear on the Home and View tabs. This is a new capability with no administrative action required.
Microsoft's description
You can now customize the classic ribbon in New Outlook for Windows and Outlook on the Web by right-clicking the ribbon and choosing which commands and groups appear on the Home and View tabs. #newoutlookforwindows