The default Outlook setting is to only show mailbox\calendar data for 1 year. To change this Outlook setting do the following;
- Open Outlook
 - Click on File
 - Click on the Account Settings button
 - Click on Account Settings in the list displayed
 - Double click your email account
 - Move the slider to your prefferred setting. The very end of the slider will display all of your emails in Outlook
 - Click on the Next button>Click on the Done button>Click on the Close button