This is the error message I get:

The message could not be sent. The authentication setting might not be correct for your outgoing e-mail [SMTP] server. For help solving this problem, go to Help, search for "Troubleshoot Windows Live Mail", and read the "I'm having problems sending e-mail" section. If you need help determining the proper server settings, please contact your e-mail service provider.

Server Error: 554

Server Response: 554 5.7.1 <email address>: Relay access denied

Server: 'mail.optusnet.com.au'

Windows Live Mail Error ID: 0x800CCC79

Protocol: SMTP

Port: 25

Secure(SSL): Yes