ATT and Windows Mail

Windows Mail and ATT has been working fine together, until recently. I am
not allowed to send mail anymore. It still receives fine. I received the
error message below.

The connection to the server has failed. Subject 'st . Agnes', Account:
'', Server: '', Protocol: SMTP, Port: 25,
Secure(SSL): No, Socket Error: 10013, Error Number: 0x800CCC0E