Add a folder to the Favorite Folders pane
When you add a folder to Favorite Folders in the Mail pane, in the Navigation Pane (Navigation Pane: The column on the left side of the Outlook window that includes panes such as Shortcuts or Mail and the shortcuts or folders within each pane. Click a folder to show the items in the folder.), the folder stays in its original location, and Favorite Folders provides quick and easy access to the folder. Only mail folders can be added to Favorite Folders.