Outlook 2013 has the ability to track the total amount of quota used and available free space of your mailbox. The following article illustrates how to view your total mailbox size and available space.
1. Open your Outlook 2013 Client.
2. In the upper left corner, click on the File tab.
3. Under Info, you will find Mailbox Cleanup and your total quota usage along with available space.
Please Note: The actual mailbox size is not shown. The total size represents the point when size-limit warnings are issued.
