If you are worried about your Deleted Items folder becoming overly large, you can configure Outlook to automatically empty the Deleted Items folder whenever you exit the Outlook application. This comes in especially handy when you have size limits on how large your inbox can be.
1. Open Outlook.
2. Go to the top of the Ribbon and click the Office Button.
3. Click on the Options button.
4. In the left pane, select Advanced.
5. Go to the Outlook start and exit section.
6. Check the Empty Deleted Items folder when exiting Outlook checkbox.
7. Click the OK button.