Although all your email addresses are migrated from GroupWise to Live@edu the new system does not use these when auto-completing. Even if you copy all your Frequent Contacts to the Microsoft equivalent of 'Suggested contacts' this does not improve.
Outlook stores your auto-complete contacts in a separate file. Unfortunately there is no straightforward way of importing contacts to that file, even if they are stored in Outlook. Over time this problem should diminish as that file is populated each time you send messages to new contacts.
Clicking the "Check Names" button - or using the keyboard shortcut Ctrl-K - is a useful way of finding matches to partially typed in addresses.