Spam Prevention/Reduction - Contact Form?

I want to add a simple Contact form to my web site so that customers can contact me easily.

<form>
    NAME
    <input type='text' name='name' />
    EMAIL
    <input type='text' name='email' />
    MESSAGE
    <textarea name='message' />
    <input type='submit' />
</form>

This form would simply email me the customers message.

But, I also want to reduce (not, I'm not saying eliminate but at least reduce), SPAM.

I've looked into using CAPTCHAs but, ultimately, I don't want to hinder the customer with having to fill out extra information.

Any ideas of a good simple spam prevention/reduction method I could use for my Contact form.

Solution 1:

A very simple trick I've been using with a surprisingly good success rate is this: Provide a text field that is hidden from human users with style="display: none", but with an enticing name like email. Most bots will fill in something in this field, but humans can't see it so they wont. At the server, just make sure the field is empty, else treat the submission as spam.

Solution 2:

If you want to do a completely front-end solution I have had success recently by leaving the form action attribute blank, and populating it via a $(document).ready function. Most spambots use a browser that has javascript disabled, or are looking for hidden fields to avoid detection.

Example:

Your html would be:

<form method="POST" action="" id="contact-form">

and anywhere in that page you can use this to populate it.

<script>
        $(document).ready(function(){
                 $("#contact-form").attr("action", "/yourMailScript.cgi");
        });
</script>

A bot browser with no javascript will not get a form action, and they will get a 404 upon submission. Anyone with a normal browser (unless they have JS disabled for paranoid reasons) will get the normal behavior.