Reporting-MTA: dns;dub0-wss1-s2.dub0.hotmail.com
Received-From-MTA: dns;DUB116-W11
Arrival-Date: Mon, 23 Sep 2013 07:41:35 -0700
Final-Recipient: rfc822;****@*****co.uk
Action: failed
Status: 5.6.2
Diagnostic-Code: smtp;554 5.6.2 Delivery SMTP Error. Command: 0. Response: 550-Your IP address is on the XBL blacklist! Sending denied.
550-For further information and delisting procedure,
550 please see http://www.spamhaus.org/query/bl?ip=********

It happens randomly, not on every email.

How can I get myself unblocked please!!