This message would normally indicate a problem with the password - are you sure there is no caps lock on when you are typing it in and have you tried resetting the password in cPanel and then trying again? I know these are simple things that you may have already have tried but they solve the problem 90% of the time. Even if you haven't typed it wrong unfortunately sometimes computers have errors so maybe you could try resetting the email address up again in both cPanel and Outlook?
Hope that helps and you get your problem sorted
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