OlActionShowOn Enumeration
Office 2010
Identifies where an Action is displayed as an available action.
Assembly: Microsoft.Office.Interop.Outlook (in Microsoft.Office.Interop.Outlook.dll)
Displaying an action on a toolbar is only supported in versions of Outlook without the Microsoft Office Fluent ribbon, before Microsoft Office Outlook 2007.In versions of Outlook that contains the ribbon, custom actions are displayed only on the Custom Actions menu on the ribbon for an inspector, and on the context menu of an item.