/**
  * Filters mail header injection, html, ... 
  * @param string $unfiltered_value
  */
 static function filter($unfiltered_value)
 {
     $mail_filtered_value = preg_replace('/(%0A|%0D|content-type:|to:|cc:|bcc:)/i', '', $unfiltered_value);
     return stripslashes(wp_filter_nohtml_kses(Affiliates_Utility::filter_xss(trim(strip_tags($mail_filtered_value)))));
 }