Filtering Spam, eventually

I've finally sat down and installed a spam/virus filter on Kemitix.net. I might start reading my email a bit more often now. I used amavis-new using clamav and SpamAssassin. At least it's claiming to. Despite enabling SA, I'm not seeing any evidence of it doing anything, other that nibbling at the processor each time a mail arrives. It isn't catching the spam, or even reporting in the headers that it even saw the main. Amavisd is however. Could it be preventing SA's header from appearing... Yup. It was only adding headers for 'local' recipients, but had the host name wrong in what it was using to consider whether they were local or not.