function mail_ajax(mode)
{
    var params = Form.serialize("mail_form");
    if (mode == "post") {
        params += "&mail_post=1";
    }
    else if (mode == "preview") {
        params += "&mail_preview=1";
    }

    new Ajax.Request("http://www.4210.info/cgi/shift/plugins/MailForm/mt-mail-form.cgi",
                     { method : "post",
                       parameters : params,
                       onComplete : displayMailResult });
    $("send_status").innerHTML = '<p>送信中です...</p>';
    return false;
}

function displayMailResult(obj)
{
    $("send_status").innerHTML = "";
    $("ajax_mail").innerHTML = obj.responseText;
}