From our SMTP server logs:

remote from [64.151.68.164]
HELO ADV-RH9-NOCP.YOUR-DOMAIN-HERE.com
554 Unresolvable HELO name: ADV-RH9-NOCP.YOUR-DOMAIN-HERE.com

There is such a thing as taking the instructions too literally. (Or perhaps the error here is in not following instructions; who knows.)

This appears to be a PLESK-based setup (judging from the web page on that IP address), which does not make me any better inclined towards these people. Sometimes I think it has become too easy to set up machines on the Internet.

For bonus points, the IP address claims to have the name 'customer-reverse-entry.64.151.68.164'.