W3C's mail servers are configured to reject messages sent with bogus HELO/EHLO greetings.
If you tried to send email to W3C and received a bounce message directing you to this page, please contact your local postmaster, system administrators, or email software vendors to ask them to help you fix the problem.
For more information on legitimate HELO/EHLO greetings, please see RFC 2821, section 4.1.1.1.