I’ve been struggling with registration spam on one of my retail websites. Currently it’s running a shop based on WordPress, so I have access to a plethora of plugins to assist with this issue. I had been using Stop Spammer Registrations, along with re-Captcha, which only worked for so long. Somehow the spammers just keep getting through, so I took the next step to fortify with Bad Behavior.
Bad Behavior is a WordPress plugin that helps stop spammers before they even access your site. To assist the plugin, it makes a call out to the http:BL API, which is available for free. Once you get the API setup, simply copying it into the plugin is the extent of the setup for normal operation. However, I ran into an issue with getting my transactions confirmed, because I believe it is blocking the callback IP from PayPal.