A data file is a Personal Folders file (.pst) (Personal Folders file (.pst): Data file that stores your messages and other items on your computer. You can assign a .pst file to be the default delivery location for e-mail messages. You can use a .pst to organize and back up items for safekeeping.).
The name of the folder associated with the data file appears in the Folder List (Folder List: Displays the folders available in your mailbox. To view subfolders, click the plus sign (+) next to the folder. If the Folder List is not visible, on the Go menu, click Folder List.). To view the Folder List, on the Go menu, click Folder List. By default, the folder will be called Personal Folders .