Nice! I have created something similar, called Konstati (http://konstati.co http://konstati.co), focusing on email marketers. So far it only tests emails agains

Nice! I have created something similar, called Konstati (http://konstati.co http://konstati.co), focusing on email marketers. So far it only tests emails against Spamassassin, providing useful tips about each SA rule (still only in portuguese, though). I'm currently working on it to support W3C validation, link and image checkers and email previews.