Email won't send

I recently developed a problem in that my email will not send.

I have updated Norton.(Norton Interney Security) No help.

I've even updated to windows live mail (was using Outlook Express 6). Still did not help.

I believe that my problems started days ago with an update from either Windows or Norton. Can not figure this out!

Error is

Server Error: 550

Server Response: 550 Access Denied

Server: mail.windjammercable.net

Windows Live Mail Error ID: 0x800CCC69

Protocol: SMTP

Port: 25

Secure(SSL): No