/** @function QPHeader Encodes given string as a quoted printable mail header. @param str string String to encode @return string */ public static function QPHeader($str, $charset = 'UTF-8') { if (!preg_match('/[^\\x00-\\x3C\\x3E-\\x7E]/', $str)) { return $str; } return '=?' . $charset . '?Q?' . text::QPEncode($str) . '?='; }