This article describes how to add an MX record to Godaddy if the DNS is hosted at Godaddy.
Create an A record for “mail”. Point the record to the primary IP where the mail will be hosted. This can be the same IP as the website or a different IP if mail in on a different server.
Now create the MX record. Replace “domain” with your actual domain name.
Allow for DNS propigation. Check the DNS at:
https://www.whatsmydns.net