The IPBL is an method to block e-mail that comes from sources that may be abusing resources on this server.
If you are viewing this page, it is likely that you have seen the message similar to:
This messages does not mean that we are accusing you of sending junk e-mail or viruses. It means that the server has been sending e-mail or viruses to honeypot e-mail ids.
If you have exclusive use of ip address then check your computers to ensure that they are no longer sending out junk e-mail or viruses.
If the ip address was dynamically allocated to you (eg by a dail-up connection) then report this abuse to your ISP.