PHP email 유효성 체크

function emailCheck($email){
if(!eregi("^[a-zA-Z0-9]+[_a-zA-Z0-9-]*(\.[_a-z0-9-]+)*@[a-z??0-9]+(-[a-z??0-9]+)*(\.[a-z??0-9-]+)*(\.[a-z]{2,4})$", $email)) return FALSE;

return $email;
}