function trim(t) {
	s=t
  while (s.substring(0,1) == ' ') {
	s = s.substring(1,s.length);
  }
  while (s.substring(s.length-1,s.length) == ' ') {
	s = s.substring(0,s.length-1);
  }
  return s;
}

function compEmail (correo){
	var filter  = /^([a-zA-Z0-9_\.\-%%])+\@(([a-zA-Z0-9\-%%])+\.)+([a-zA-Z0-9]{2,4})+$/;
	if (filter.test(trim(correo)))
		return true;
	else 
		return false;
}