function validar() 
{    
    var patronMail =  /^[^@ ]+@[^@ ]+.[^@ .]+$/;
    if(String(document.form1.email.value).search(patronMail) < 0)
    {
        alert ("You must type a valid email");
        document.form1.email.focus(); //Esto recorna el cursor al campo "Email"
        return false;
    }

    return true;
}