I did a test e-mail using my Gmail account and this bounced back:
Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the server for the recipient domain (mydomain.com) by smtp.secureserver.net. [72.167.238.29].
The error that the other server returned was:
550 5.1.1 <(myemail@mydomain)> Recipient not found. <http://x.co/irbounce>
Help would be appreciated!