Hi,
I've just uploaded to sourceforge the first version of a spamvertised URIs pre-queue filter for Postfix.
It's simple and effective. It will analyse the message before it enters the queue and, in case of a listed url, it will REJECT the message and the sending client will take the proper actions.
http://prdownloads.sourceforge.net/pf-aux/suriproxy-0.8.tar.gz?download
See the readme file for instructions.
I can't assure how stable it is at the momment, that's why I am asking some feedback. What do you think?