I would like to try your plugin, but just want to make sure I'm using the correct template code:
<?php do_action('plugin_name_hook'); ?>
and not something like?
<?php do_action('spam_ip_blocker'); ?>
Any way you can add a self-test/method to indicate in the WP backend that the plugin has correctly been activated and is working? Right now, I have no way of knowing this.
Also, maybe, a way of showing which IPs have been blocked?