Do one of the following:
Create a new data file Personal Folders file (.pst) and drag items to it. If you used the default name for the folder when you created the data file, the folder will be called Personal Folders. In the Folder List, drag any item from your current folders to the new folder. Press CTRL while dragging to copy items instead of moving them.
Export (copy) items to a Personal Folders file (.pst). You can only export one folder at a time, but you can include the subfolders under that folder. For example, you can export your entire [Mailbox - Username] including all subfolders.
If you want to automatically back up or delete items that are over a certain age
Use AutoArchive to move items to an archive Personal Folders file (.pst). Unlike exporting, where the original items are copied to the export file but are not removed from the current folder, archiving copies items to the archive file and then removes them from the current folder. AutoArchive allows you to set up a schedule and archive multiple folders at the same time at set intervals.