replace overcomplicated regex for email validation with php function

includes/sys_page.php

@@ -43,7 +43,7 @@ function strip_item($item) {
  * Überprüft eine E-Mail-Adresse.
  */
 function check_email($email) {
-  return (bool) preg_match("#^([a-zA-Z0-9_+\-])+(\.([a-zA-Z0-9_+\-])+)*@((\[(((([0-1])?([0-9])?[0-9])|(2[0-4][0-9])|(2[0-5][0-5])))\.(((([0-1])?([0-9])?[0-9])|(2[0-4][0-9])|(2[0-5][0-5])))\.(((([0-1])?([0-9])?[0-9])|(2[0-4][0-9])|(2[0-5][0-5])))\.(((([0-1])?([0-9])?[0-9])|(2[0-4][0-9])|(2[0-5][0-5]))\]))|((([\p{L}0-9])+(([\-])+([\p{L}0-9])+)*\.)+([\p{L}])+(([\-])+([\p{L}0-9])+)*))$#u", $email);
+  return (bool) filter_var($email, FILTER_VALIDATE_EMAIL);
 }
 
 ?>