API?

There isn't a way to do this currently, but it could certainly be done. In fact, I'd recommend that one be EXTREMELY careful with this. If, for example, you ran "http://example.com", you might be tempted to have a URL like "http://example.com/troll/insta-block" that would instantly block the user's IP. That could easily work. Maybe you would do it so that spam bots couldn't play with your site. Here's the problem though: what happens if we have a malicious user? If they want to block "Bob" from the site, they could send him an HTML email with in it. This would cause Bob's computer to make a request to that URL even though he didn't realize he was being setup. This would effectively provide a way for an malicious user to block anyone (including you) from the site.