This article illustrates how to view your total mailbox size and free/available space within your mailbox account using Outlook 2010.  

1. Open Outlook 2010. 

2. Click the File tab.   

 3. Click Info.  

4. Review the data under "Mailbox Cleanup".  

IMPORTANT: Please note the actual mailbox size is not shown. The total size represents the point when size-limit warnings are issued.