Your system administrator typically backs up your network mailbox on a regular basis. You can back up your local mailbox if you want to have an additional copy of your mailbox, or if you want to back up information that is no longer in your network mailbox.
You should periodically back up your Mailbox Caching Directory to a different location. If the Caching Mailbox should become corrupted, you can either make a new Caching mailbox based on your current Online mailbox or restore your backup into your Caching mailbox directory.