I had this same issue with my domain. there should be a link in the error message. My problem was because my IP address that I get from my ISP is a DHCP address. If yours is then your address automatically gets added to the Spamhaus list. It is easily corrected. Go to <a href=”http://www.spamhaus.org/”>www.spamhaus.org</a> and go to the link in the middle of the page that says REMOVE IP ADDRESS. That page will give you more information on the problem and a way to fix it.
Additionally, if your IP Address is assigned to you in a pool of addresses it’s entirely possible that your server is being used to send spam– especially if you are removing it every day.
If your IP address comes from a DSL or cable provider, the first is a likely possibility. However, if you’ve been given a pool of addresses from Sprint, or some other T1/T3 carrier into your office you’ve likely got a spammer (or 500) using your server as a relay.
checking to see what list, (SBL, XBL, or PBL), your IP address is listed on will help determine if spammers are using your server as a relay