Name based RBL scoring

[Sam Hayes Merritt, III]

I've searched and cannot find so I'm hoping someone can help.
We have a RBL we host that contains the domain names of dynamic hosts, 
spammers and other we do not want to receive email from.

Currently in sendmail we use the revised dnsbl.m4 from Derek Balling 
(http://www.megacity.org/software_downloads/dnsbl.m4) which looks up the 
hostname of the connecting machine against a RBL. I'm trying to duplicate 
that in Sendmail as it provides us a lot of usefulness and would get us 
away from the blanket rejects.

Are there any rules written to do this in Spamassassin? I see IP RBLs and 
I see RHSRBL, but I don't see domain-based RBLs that check the connecting 
machine.



Thanks,

sam