function joinNewsletter()
{
    var email = document.getElementById("email_address").value;
    
    if ((email == null) || (email == ""))
        alert("Please enter your e-mail address.");
    else
        window.open( 'http://oi.vresp.com?fid=7bfdd25915&email_address=' + email, 'vr_optin_popup', 'scrollbars=yes,width=600,height=450' );
    
    document.getElementById("email_address").value = "";
    
    return false;
}