Windows NT "Messenger Service" has nothing to do with instant messaging
client software, like AOL, MSN, or Yahoo's Messenger programs. If you
want integration enabled between Outlook and MSN Messenger then enable
it in the options (tools -> options -> other). Be prepared for long
delays when trying to read items in your Inbox; for each one, MSN
Messenger will get called by Outlook to go check on the status of the
sender (after first checking the sender is in a contact-type folder
which is included in Outlook Address Book and that you recorded their
MSN Messenger userid in their contact record).