add_filter('wpcf7_validate', function ($result, $tags) { // 1. 检查 referer(来源) if (!isset($_SERVER['HTTP_REFERER']) || strpos($_SERVER['HTTP_REFERER'], $_SERVER['HTTP_HOST']) === false) { $result->invalidate('', 'Spam detected'); return $result; } // 2. 检查 user agent(很多机器人是空的) if (empty($_SERVER['HTTP_USER_AGENT'])) { $result->invalidate('', 'Spam detected'); return $result; } // 3. 屏蔽常见垃圾邮箱域名 if (isset($_POST['txtemail'])) { $email = $_POST['txtemail']; if (preg_match('/@(mail\.ru|legenmail\.com|cialis-otc\.com|bekommenmail\.com)$/i', $email)) { $result->invalidate('txtemail', 'Spam email domain blocked'); return $result; } } return $result; }, 10, 2);