Spambots unite!

While not a solution for email, Phil Haack talks about a simple way to help prevent spam bots from attacking your forms on your web sites.  By using an invisible captcha, one can defeat most bots. 

First, what is a Captcha?  It is a challenge - response test to help determine that you are actually a human.  You've undoubted already came across a few of these during a sign up process of some text with a grid or a line through it asking what it says.

Haack came to the conclusion that most bots don't do two things, parse CSS and execute JavaScript.  Haack's solution adds in a field in a hidden div tag that a spam bot would fill then checks it server side during the validation of the submission.  He even wrote a validation control which is on CodePlex.