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 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.
The rejected e-mail address was '*** Email address is removed for privacy ***'. Subject 'Points values', Account: 'mail.o2.co.uk', Server: 'smtp.o2.co.uk', Protocol: SMTP, Server Response: '550 RCPT TO:<*** Email address is removed for privacy ***> Relaying not allowed - please use SMTP AUTH', Port: 25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC79