DNSBL, Spamhaus and postscreen filters

[Robert Sharp]

I was prompted from reading a recent post to check whether my postscreen 
set up was picking up Spamhaus responses. Quick grep through my logs 
confirmed that it was not. Seems I am in a bit of Bind (sorry for the 
pun). If I use Google's DNS I dont get a response from zen.spamhaus.org. 
If I use my ISP's DNS I will but my ISP also hijacks NXDOMAIN responses 
as I was reminded last night when postscreen blocked everything. I am 
now looking at setting up my own unbound server, but I wondered if there 
was a quicker solution. Can I use the filter option to ignore those 
hijacked responses? For example:

postscreen_dnsbl_sites = zen.spamhaus.org=127.0.0.[0..127]*3
I would just give it a go but after blocking everything I am a little 
cautious today. Yes, I could add soft bounces but...

Thanks for any help