I also have Office 365 from GoDaddy and cPanel hosting. You do NOT need a plugin to get this working. +1 to chemusic, his fix worked. -1 to the plugin author for lying and trying to call his comment spam. His solution worked.
I logged into my GoDaddy cPanel account. Deleted the default mx entry (which was set to deliver mail locally through cPanel and not through Office 365 as a remote. Added a new REMOTE entry that matched my mx record from my domain. Took about 10 mins to get me up and going. WITHOUT the plugin.