1. Open Outlook 2010.
2. Click on File.
3. Under the Info header, click on the Account Settings button and then on the Account Settings tab.
4. Click on Change.
5. Click the More Settings button.
6. Click on the Advanced tab and then click on Add.
7. Enter the email address of the delegated mailbox in the Add mailbox field.
8. Click on Apply and then on OK. Outlook will now be busy accessing the other mailbox’s data, so this may take a while.
9. Back on the Change Account window, click on Next and then on Finish.
10. Close the Account Settings window. You should now see both mailboxes in your Outlook profile.