Some users complaining on SPAM issues, even when using standard captcha. We implemented recaptcha for this case in v1.5.9

Guide:

1. Update script to min. v1.5.9, guide to update is available on bottom of item page where you purchased product, and can be downloaded on same place as you download product
2. Get your recaptcha keys on page: https://www.google.com/recaptcha
3. Insert recaptcha keys in application\config\cms_config.php:
$config['recaptcha_site_key']   = "your-site_key";
$config['recaptcha_secret_key'] = "your-secret_key";

Also your server should have in php.ini or recaptcha will not work properly:

allow_url_fopen = On;

Standard captcha is supported from v1.4.9 and is included by default: http://iwinter.com.hr/support/?p=54