I have the same problem. But...
1- My site is this: http://www.bike.pro.br
2- My email has the same domain, but configured in Office365
3- I do not want to create another email to use in Gadaddy. Mainly because Godaddy has limited the number of emails sent per hour. I have many subscribers on my site receiving notifications every post I publish.
Precisely for this limitation I'm paying the Mail Exchange in order to send emails to all my subscribers at once.
I need my Wordpress hosted on Godaddy be able to send my emails through the Mail Exchange.
Can someone help me?