In Microsoft Outlook, AutoArchive is on by default and runs automatically at scheduled intervals, removing old and expired items from folders. Archived items remain available to you in the default location, Archive Folders in the Navigation Pane, or in a location that you specify.
For more information on archiving items, including how to archive items manually, see Back up, restore, or delete items using AutoArchive.
To find and open your archived items, do one of the following:
On the Go menu, in the Folder List, click Archive Folders (or the name you specified for the archive location).
In the Navigation Pane, under All Folders, in the Folder List, click Archive Folders (or the name you specified for the archive location).
If your archive folders and items don’t appear in the Navigation Pane, the data file might have been closed. To open the archive data file, do the following:
On the File menu, point to Open, and then click Outlook Data File.
Click the archive .pst file that you want to open, and then click OK.