how to add ribbon to outlook web application
Applies to: The information in this topic applies to VSTO add-in projects for Outlook. For more information, see Features Available by Office Application and Project Type. Adding a Custom Ribbon to the Main Application UI. The main application UI in Outlook is called the Explorer.If you are using the Ribbon (Visual Designer) item, you can add a ribbon to the Explorer by clicking the RibbonType property of the ribbon in the Properties window, and then selecting Microsoft.Outlook.Explorer.ou identify the inspector you want to customize by specifying the ribbon type that corresponds to the message class for the Inspector. If you are using the Ribbon (Visual Designer) item, click the RibbonType property of the ribbon in the Properties window, and then select one or more ribbon IDs from the list of values.