Problem sending outgoing mail from my iPhone

I was referred here by the help staff on Twitter. I have been having trouble sending outgoing mail on my iPhone. The error says " Cannot Send Mail. The user name or password for *** Email address is removed for privacy ***@smtp.live.com is incorrect.  However, the password is correct and the same for my incoming mail which I am receiving. I had the same problem last week and the genius desk at Apple helped me by deleting and reinstalling the account. It worked but now same problem and this time deleting and reinstalling isn't working. I'm not sure why this is happening...could it be the change to Outlook?  It seems the problem started shortly after. I look forward to your help.