HTML coding needed -- site being abused

[TheMenuMaker]

I have a form on my website that is being used to send me advertising weblinks -- they vary from educational links to porn. While it's no big deal to simply delete the messages from my inbox, I'm getting a little pissed. And they are increasing daily!!

What I need is to add something to the form that will put a stop to it -- like a security box of 5 digits the user has to enter before sending. But I don't know how to code that sort of thing. Do you know, or do you know where I can find how? (I'm also open to other ideas)

Thanks in advance,
Jane, The Menu Maker

[deronsizemore]

Are you using any kind of CMS? A lot of the open source ones out there have plugins to do exactly what you're looking for. It's called a captcha I believe.

[Nico]

Like deronsizemore said, what you are refering to is called "CAPTCHA". It's a great way to prevent spam and to make sure that a real person is using your forms:

http://phpsec.org/articles/2005/text-captcha.html
http://codewalkers.com/tutorials/95/1.html

I hope it helps.

[Chris]

Additionally consider changing your form some to throw them off.

1. Check to see what the HTTP_REFERER is when processing the form, if it isn't your site, don't process it.

2. Name your submit button and check for it's existence before processing the form. If they're using an automated process they likely include all your form variables, but they usually forget the button.

3. If these checks fail, tell them it worked anyway.

4. Include IP addresses with all messages sent, so you can ban repeat offenders.

[shyampc]

Those links to article and tutorial is very helpful. Thanks for sharing it. Do you have any tutorials for creating the forms for websites using HTML? Can captcha be used with HTML?