function wpcf7_validate_spam_message( $result, $tag ) {
$value = str_replace(array(PHP_EOL,' '), '', esc_attr($_POST['your-subject']));
if (!empty($value)) {
if (preg_match('/^[!-~]+$/', $value)) {
$result['valid'] = false;
$result['reason'] = array('your-subject' => '日本語で入力してください');
}
}
return $result;
}
add_filter( 'wpcf7_validate', 'wpcf7_validate_spam_message', 10, 2 );