function suscribir_boletin( _ema ){
    if( _ema == ""){
        window.alert("Enter the email");
    }
    else{
        var filter = new RegExp(/^[a-z][\w|\.]*@[\w]*\.([a-z]{2,4}|[\a-z]{2,4}\.[a-z]{2,3})$/);
        if( !filter.test( _ema ) ){
            window.alert("Enter a valid email");
        }
        else{
            enviar('suscribir_boletin.php','email='+_ema,'evaluar','');
        }
    }
}