1. Can you log in to mail.letu.edu?  If yes, restart Outlook.
  2. Use your UserName@letu.edu email address when prompted for credentials and check the "remember credentials" box.
    If prompted again, click Cancel. 
    If prompted again after Cancel, move on to step 3.
  3. Verify that prompt for Credentials isn’t checked in profile:

Mac Outlook -- Choose Tools | Accounts | type your LETU password in the password field.  Close the Accounts window.  

4. Clear your cached passwords (Note: you may need Admin rights to do this) - Windows

Clear your cached password - Mac

5. Rename the Outlook .ost file (if get error about "cannot open set of folders")

6. Creating a New Profile (when you create a new profile, you will need to re-add any email account you check including shared departmental accounts)

NOTE:  you will need to reopen any .pst or archive files you have.