Hi I am using Windows Live Mail and as of yesterday, I cannot send any emails but can still recieve.  The message I get is as follows;

An unknown error has occurred.

Subject 'neo'
Server Error: 554
Server Response: 554 nskntcmgw07p BigPond Outbound [OB105. Connection refused. 121.219.230.47 is listed on the Exploits Block List (XBL). Please visit http://www.spamhaus.org/xbl/ for more information.
Server: 'mail.bigpond.com'
Windows Live Mail Error ID: 0x800CCC6F
Protocol: SMTP
Port: 25
Secure(SSL): No

Can any one help me?  I have been on the spamhaus website and followed some instructions, but as far as I can tell the above IP address is not mine.

Thanks in advance!!