Hi
i am looking for anti-spam Captcha script in order to avoid spam mails on my site's contact us form.
thanx
PHP Anti-Spam Captcha Script
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If the spammer is automated you could use a question to vaildate like,
How much is twenty4 times 2, then have the answer to validate. Quite easy for a human but not so for a bot, maybe at the moment but they are out there. Spam bots do look for for login pages/forums standard form boxes so you can also alter your login page to suit and all links on your website could be images eg
<a href="http://www.phpbb.com/" target="_phpbb" class="copyright"><img src="templates/subSilver/images/Powered by.JPG" width="234" height="14" alt="" border="0"> with the href linking it so the bot may not pick the text info up. I picked up some useful info off forum phpbb site, it may Help
I frequently use one of two Captcha facilities for PHP forms:
http://www.captcha.ru/en/kcaptcha/
http://recaptcha.net/plugins/php/
Both are quite easy to install.