AskDNS with a DNAME

[Damian]

I don't know about AskDNS, but this technique works with stock spamhaus rules 
via spamhaustech. I have a local spamhaus.net zone with a DNAME record as their 
nameservers block me anyway.
You could try with an invaluement.com zone at least temporarily as a comparison 
to AskDNS.