I'm receiving the following error when trying to send e-mail using Windows Live.  I can receive, but not send.

Server Error: 554

Server Response: 554 Transaction failed : Cannot send message due to possible abuse; please visit http://postmaster.yahoo.com/abuse_smtp.html for more information

Server: 'smtp.att.yahoo.com'

Windows Live Mail Error ID: 0x800CCC6F

Protocol: SMTP

Post: 465

Secure(SSL): Yes

Does anyone know what is causing this and the solution?