for several days I have been unable to send email though can receive ok.
this error message appears:
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 'godeans@gofast.co.uk'. Subject 'youtube',
Account: 'mail.o2.co.uk', Server: 'smtp.o2.co.uk', Protocol: SMTP, Server
Response: '550 RCPT TO:<godeans@gofast.co.uk> Relaying not allowed - please
use SMTP AUTH', Port: 25, Secure(SSL): No, Server Error: 550, Error Number:
0x800CCC79

please can anyone help??