Author: L.Ling2 (18 Sep 16 8:03pm)
Are you still seeing these errors?
Generally, the servfail error indicates that the DNS you queried was unable to answer your request, most likely due to a misconfiguration of that server. The error unexpected rcode indicates that the response that the DNS server got (either from another server or its own memory) isn't formatted correctly for the type of record.
I don't have a key, so I can't check the DNS directly, and I haven't read all of the docs on the httpBL, but I'm guessing that your system is asking for IPs (A records) and getting text (TXT records).
The other possibility is that there is a recursive server somewhere that isn't handling EDS correctly (or maybe the firewall the server is behind).