Microsoft changed quite a lot of the user interface elements in Office 2010, and personally I think Outlook was most affected by this. This guide will show you how to add additional mailboxes in Outlook 2010.
Example: “I recently got upgraded to Microsoft 2010. How can I add back my mailboxes?”
Resolution: Open Outlook and click on File > Info > Account Settings > Account Settings. Highlight the user’s Outlook profile and click Change. Then click on More Settings > Advanced and add more mailboxes from there.