function validar(formulario) {

if (formulario.email.value == "")
{
alert("E-Mail is Empty. You should fill in.");
return false;
}
if(checkEmail(formulario.email)==false)
{
 return false;
}
if( validarformato(formulario.recuadro,"no",0,8)==false )
{
 return false;
}  
document.formulario.submit();

}

 function validarformato(variable,cadena,mirar,longitud) 
 {
 cadena1 = variable.name;
  cadena1=cadena1.replace("_" ," ");
    cadena1=cadena1.replace("_" ," ");

 if (variable.value.length == 0 && mirar == 1)
  {
  return true;
  }
 if (variable.value.length < longitud) {
           alert("Too short."+ variable.name);
    variable.focus();
    return (false);
  }
   
 if (cadena == "si"){
  var checkOK = "ABCDEFGHIJKLMNÑOPQRSTUVWXYZÁÉÍÓÚ.," + "abcdefghijklmnñopqrstuvwxyzáéíóú ";
  var checkStr = variable.value;
  var allValid = true; 
  for (i = 0; i < checkStr.length; i++) {
    ch = checkStr.charAt(i); 
    for (j = 0; j < checkOK.length; j++)
      if (ch == checkOK.charAt(j))
        break;
    if (j == checkOK.length) { 
      allValid = false; 
      break; 
    }
  }
  if (!allValid) { 
   alert("Only letter "+variable.name);  
    variable.focus(); 
    return (false); 
  }}
   if (cadena == "numerico"){
  var checkOK = "0123456789- " ;
  var checkStr = variable.value;
  var allValid = true; 
  for (i = 0; i < checkStr.length; i++) {
    ch = checkStr.charAt(i); 
    for (j = 0; j < checkOK.length; j++)
      if (ch == checkOK.charAt(j))
        break;
    if (j == checkOK.length) { 
      allValid = false; 
      break; 
    }
  }
  if (!allValid) { 
    alert("Only number "+variable.name);  
    variable.focus(); 
    return (false); 
  }}  

 return true
 }
function checkEmail(valor) {
if (valor.value == 0) return true;
  if (/^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/.test(valor.value) )
  {
   return true;
  } else {
      alert("The e-mail is wrong: " + valor.value    + ".") 
valor.focus();
   return (false);
  }
 }