Add-IPBlockListProvider -Name zen.spamhaus.org -LookupDomain zen.spamhaus.org -AnyMatch $True -Enabled $True -RejectionResponse “Your IP is blacklisted! http://www.spamhaus.org“

This script adds new provider called zen.spamhaus.org, makes lookups to zen.spamhaus.org and it works on any reply (127.0.0.1,2 …), it does enable this provider and it sets response that is sent to sender.