IP'S aren't tied to anyone in particular. Its very possible there was a spambot or such robot server on the IP address you currently have, and that IP was blocked. Then, said server loses IP for whatever reason and it goes back to the DHCP pool. Now, you come along one day and your ISP gives you that IP address for your modem. Boom, you are now blocked.
So, you just have to send that email so they can unblock your IP. In the mean time, they will probably block another IP that is causing problems.
It's easy for me to say, block all of russia or china on my .htaccess file for my blog. But, when you have a site (like FISD) that is meant to allow access to members all over the world, you can't just out right block a country that is known for robots. The only other option is to block IP's, which unfortunately can affect real people sometimes.
Cat and mouse game it is.