function validaForm(){

	r=document.letter;
	email=r.email.value;
	number=r.number.value;
	
	if(number==""){
		alert("Attention you have not inserted the ALPHANUMERIC text!")
		r.number.focus(); 
		return false; 
	}
	if(number!="AZ5R"){
		alert("Attention Controls inserted letters!")
		r.number.focus(); 
		return false; 
	}
if(email==""){
		alert("Attention you have not inserted the email");
		r.email.focus(); 
		return false; 
		}
	if(email!=""){
	Filtro = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-]{2,})+\.)+([a-zA-Z0-9]{2,})+$/;
   if (Filtro.test(email))
      return true;
   else
      {
      alert("Wrong address email!");
      r.email.focus();
      return false;
      }
	}

return true;
}