Microsoft Outlook – Auto-added Javascript in e-mail signature

I’m having a problem with the signature in Outlook. Apparently when I send an email from Outlook a commented Javascript code snippet is automatically added.

<script language="JavaScript"><!--
function msoCommentShow(anchor_id, com_id)
{
    if(msoBrowserCheck()) 
        {
        c = document.all(com_id);
        a = document.all(anchor_id);
        if (null != c && null == c.length && null != a && null == a.length)
            {
            var cw = c.offsetWidth;
            var ch = c.offsetHeight;
            var aw = a.offsetWidth;
            var ah = a.offsetHeight;
            var x  = a.offsetLeft;
            var y  = a.offsetTop;
            var el = a;
            while (el.tagName != "BODY") 
                {
                el = el.offsetParent;
                x = x + el.offsetLeft;
                y = y + el.offsetTop;
                }
            var bw = document.body.clientWidth;
            var bh = document.body.clientHeight;
            var bsl = document.body.scrollLeft;
            var bst = document.body.scrollTop;
            if (x + cw + ah / 2 > bw + bsl && x + aw - ah / 2 - cw >= bsl ) 
                { c.style.left = x + aw - ah / 2 - cw; }
            else 
                { c.style.left = x + ah / 2; }
            if (y + ch + ah / 2 > bh + bst && y + ah / 2 - ch >= bst ) 
                { c.style.top = y + ah / 2 - ch; }
            else 
                { c.style.top = y + ah / 2; }
            c.style.visibility = "visible";
}   }   }
function msoCommentHide(com_id) 
{
    if(msoBrowserCheck())
        {
        c = document.all(com_id);
        if (null != c && null == c.length)
        {
        c.style.visibility = "hidden";
        c.style.left = -1000;
        c.style.top = -1000;
        } } 
}
function msoBrowserCheck()
{
    ms = navigator.appVersion.indexOf("MSIE");
    vers = navigator.appVersion.substring(ms + 5, ms + 6);
    ie4 = (ms > 0) && (parseInt(vers) >= 4);
    return ie4;
}
if (msoBrowserCheck())
{
    document.styleSheets.dynCom.addRule(".msocomanchor","background: infobackground");
    document.styleSheets.dynCom.addRule(".msocomoff","display: none");
    document.styleSheets.dynCom.addRule(".msocomtxt","visibility: hidden");
    document.styleSheets.dynCom.addRule(".msocomtxt","position: absolute");
    document.styleSheets.dynCom.addRule(".msocomtxt","top: -1000");
    document.styleSheets.dynCom.addRule(".msocomtxt","left: -1000");
    document.styleSheets.dynCom.addRule(".msocomtxt","width: 33%");
    document.styleSheets.dynCom.addRule(".msocomtxt","background: infobackground");
    document.styleSheets.dynCom.addRule(".msocomtxt","color: infotext");
    document.styleSheets.dynCom.addRule(".msocomtxt","border-top: 1pt solid threedlightshadow");
    document.styleSheets.dynCom.addRule(".msocomtxt","border-right: 2pt solid threedshadow");
    document.styleSheets.dynCom.addRule(".msocomtxt","border-bottom: 2pt solid threedshadow");
    document.styleSheets.dynCom.addRule(".msocomtxt","border-left: 1pt solid threedlightshadow");
    document.styleSheets.dynCom.addRule(".msocomtxt","padding: 3pt 3pt 3pt 3pt");
    document.styleSheets.dynCom.addRule(".msocomtxt","z-index: 100");
}
// --></script>

I noticed that the code is added only if there is an image in the signature. Does anyone know how to prevent this code from being added automatically?

Thank you.