Create appointment without sending email to user

Hi,

I'm using the following code to create appointments:

Code:

---

<CreateAppointmentRequest xmlns="urn:zimbraMail">
    <m>
        <e a="'. $email .'" t="t" />
        <su>'. $title .'</su>
        <mp ct="multipart/alternative">
            <mp ct="text/plain">
                <content>'. $content .'</content>
            </mp>
            <mp ct="text/html">
                <content></content>
            </mp>
        </mp>
        <inv allday="0" status="TENT" loc="Example" name="'. $content .'" type="event">
            <s d="'. $startTime .'"/>
            <e d="'. $endTime .'"/>
            <at a="'. $email .'" role="REQ" />
            <or a="'. $this->admin_user .'" />
        </inv>
    </m>
</CreateAppointmentRequest>
</soap:Body>
</soap:Envelope>

---

How can i create this appointment without sending an email?