If you are using RBL lists for help with anti-spam then it might be worth you checking out Open Relay Database at http://ordb.org/. It is closing down as of today, so you are best removing it from your filters if in use.

First I've heard of that, do you know of any reason why that came about?

P.S. I hate spam with a passion!

I cant remember to be honest. I think it was something along the lines of finding time to support a project that was run for free.