Hi!
No, that wont work. The spams are sended in via trojans/proxys only the websites are static. SOME are blocked with DSBL and so but most of the time they start a spamrun with a fresh set it seems.
So yes, they are inside spamhaus, but only the websites, didnt see mails sended out from there (yet).
Are their NS records listed in the SBL?
Some, not all i think. Could run some tests on a larger dataset and cut out the nameservers... to check.
Bye, Raymond.