function validEmail(email) {
	var filter = /^([+a-zA-Z0-9_.-])+@(([a-zA-Z0-9-])+.)+([a-zA-Z0-9]{2,4})$/;
	if (!filter.test(email)) return false;
	return true;
}

function validImei(s) {
	var etal = /^[0-9]{15}$/;
	  if (!etal.test(s))
	    return false;
	  sum = 0; mul = 2; l = 14;
	  for (i = 0; i < l; i++) {
	    digit = s.substring(l-i-1,l-i);
	    tp = parseInt(digit,10)*mul;
	    if (tp >= 10)
	         sum += (tp % 10) +1;
	    else
	         sum += tp;
	    if (mul == 1)
	         mul++;
	    else
	         mul--;
	    }
	  chk = ((10 - (sum % 10)) % 10);
	  if (chk != parseInt(s.substring(14,15),10))
	    return false;
	  return true;
}