Automatically archive or back up Outlook items
Time Machine is an application included with Mac OS X that backs up your computer. If you turn on Time Machine, it automatically makes copies of every file on your computer on a regular basis. If any file gets damaged or lost, you can use Time Machine to browse through the backups and recover the copy of the file.
Do any of the following:
Turn on Time Machine to automatically archive Outlook items
Stop automatically archiving Outlook items