Just fill out the form at the bottom of http://www.nachi.org/nae.htm and mail it in.
Nick the email address is no good as I just tried sending it.
Delivery to the following recipient failed permanently:
Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the recipient domain. We recommend contacting the other email provider for further information about the cause of this error. The error that the other server returned was: 550 550 #5.1.0 Address rejected email@example.com (state 14).