Dave Neary (bolsh) posted an interesting blog about the RBL and blocked addresses. We are a site that blocks all of France, but not because of any "Freedom Fries" issues. :) The City of Largo has tasked us with providing a hostile-free environment, and part of that is very aggressive cleaning of email. People like to complain if they know they can, and we were getting flooded with email that was 'offending' people, which means for some being one step away from a lawsuit. The RBL has helped us block ISPs that are not actively going after spammers on their network. The theory is that the user community will give them so many support calls about email being blocked (like you!), that they will hire enough people to manage the network better. As for blocking entire countries, there is a reason for this. Spam appliances do a forward and reverse DNS check on sites as part of the first check. If this passes, filters are applied and then it's released into our GroupWise server. Our observations indicated that certain countries were sending out a great deal of spam that was getting through more than others. France (.fr) unfortunately was one of the top senders. Possibly, only about 5 out of 750 of us receive email from other countries, so we had to make the decision to block and work out exceptions as they come up.
I did a live snapshot of our spam appliance running, you can see the scope of our problems. I am sure many of you are dealing with the same thing.