Shoutbox

If you are familiar with the Windows Start Menu, right-click on the icon of Start Menu, and click Properties, after the Properties window loads, click on the Start Menu tab.

Click customize..., then at the bottom of the next window, there are these words: 'show on start menu'
Below it is your default internet browser and default email browser, change the Email Browser to Outlook.

EDIT: This only works if you have configured Outlook for your MSN Emails.