Fatal error : Call to undefined function filter_var() http://php.net/manual/en/function.filter-var.php This function is available only for PHP 5 >= 5.2.0 http://php.net/manual/en/filter.filters.sanitize.php <?php /*fix for older php version*/ if (!function_exists('filter_var')){ define(FILTER_VALIDATE_EMAIL,'/^[A-Za-z0-9-_.+%]+@[A-Za-z0-9-.]+.[A-Za-z]{2,4}$/'); function filter_var($string, $filter_type) { if ( preg_match( FILTER_VALIDATE_EMAIL, $string ) ) { return true; } return false; } } $val = 'argento@emailsamplex.com'; if (filter_var($val, FILTER_VALIDATE_EMAIL) === false) { die("$val wrong email");} echo 'ok';