Updating Earlier Code for CommandBars
In versions prior to Outlook, Outlook implemented the following items in the user interface as command bars:
Menu bars, toolbars, and shortcut menus.
Menus on menu bars and toolbars.
Submenus on menus, submenus, and shortcut menus.
Command bars have been deprecated since Outlook. Explorer and inspector windows no longer use menu bars and toolbars. Instead, they use the Microsoft Office Fluent ribbon. Programmatically, although your add-in or VBScript code that customized command bars in an explorer or inspector might still work in Outlook, those who use your solution might not easily find the customizations that appear on the Add-ins tab of the customized ribbon in the explorer or inspector.
Instead of using the CommandBars property of the Explorer and Inspector objects, use ribbon extensibility to customize the ribbon and to customize any menus and submenus off the ribbon. Ribbon extensibility requires an add-in that implements the IRibbonExtensibility interface. For more information about customizing the ribbon in Outlook, see Overview of Customizing the Ribbon.
Consistent with the deprecation of command bars in the explorer and inspector windows, do not rely on the CommandBar object for your custom menus; instead, use an add-in through the IRibbonExtensibility interface to extend them. For more information, see Customizing Shortcut Menus.