function pruefen() {
if (document.forms['newsbox'].elements['email'].value.indexOf('@',0) == -1 || document.forms['newsbox'].elements['email'].value.indexOf('.',0)== -1){

alert('Bitte geben Sie eine gültige Absender Emailadresse ein.');
document.forms['newsbox'].elements['email'].focus();
return false;
}
var breite=300;
var hoehe=200;
var positionX=((screen.availWidth / 2) - breite / 2);
var positionY=((screen.availHeight / 2) - hoehe / 2);
if(document.forms['newsbox'].aktion[0].checked){
var aktion2="eintragen";
}
if(document.forms['newsbox'].aktion[1].checked){
var aktion2="austragen";
}
var url='http://www.gastbuch24.de/gnews.php?user=ZooCenterMeerwasser&email='+document.forms['newsbox'].elements['email'].value+'&aktion='+aktion2,
pop=window.open('','', 'toolbar=0,location=0,directories=0,status=0,menubar=0,scrollbars=0,resizable=0,fullscreen=0,width='+breite+',height='+hoehe+',top=10000,left=10000');

pop.resizeTo(breite,hoehe);
pop.moveTo(positionX,positionY);
pop.location=url;
return false;
}

document.writeln("<form name=\"newsbox\" method=\"post\" action=\"#\" onSubmit=\"return pruefen()\">");
document.writeln("<table width=\"210\" border=\"0\" cellspacing=\"0\" cellpadding=\"4\" height=\"100\">");
document.writeln("<tr bgcolor=\"#006699\">");
document.writeln("<td colspan=\"2\">");
document.writeln("<div align=\"center\"><font size=\"2\"><b><font face=\"Verdana, Arial, Helvetica, sans-serif\" color=\"#FFFFFF\">Newsletter</font></b></font></div>");
document.writeln("</td>");
document.writeln("</tr>");
document.writeln("<tr>      <td width=\"43%\" bgcolor=\"#CCCCCC\">");
document.writeln("<div align=\"right\"><font size=\"2\" face=\"Verdana, Arial, Helvetica, sans-serif\" color=\"#000000\">eMail:</font></div>");
document.writeln("</td>      <td width=\"57%\" bgcolor=\"#CCCCCC\">");
document.writeln("<input type=\"text\" name=\"email\">");
document.writeln("</td>    </tr>    <tr bgcolor=\"#CCCCCC\">      <td colspan=\"2\">");
document.writeln("<div align=\"center\"><font face=\"Verdana, Arial, Helvetica, sans-serif\" size=\"2\" color=\"#000000\">"); 
document.writeln("<input type=\"radio\" name=\"aktion\" value=\"eintragen\" checked> eintragen");
          
document.writeln("<input type=\"radio\" name=\"aktion\" value=\"austragen\">austragen</font> </div>");
document.writeln("</td>    </tr>    <tr bgcolor=\"#CCCCCC\">       <td colspan=\"2\"> ");
document.writeln("<div align=\"center\">           <input type=\"submit\" name=\"Abschicken\" value=\"Abschicken\"><br><font size=\"1\" face=\"Verdana, Arial, Helvetica, sans-serif\" color=\"#000000\">&copy; by </font><a href=\"http://www.gastbuch24.de\" target=\"_blank\"><font size=\"1\" face=\"Verdana, Arial, Helvetica, sans-serif\" color=\"#000000\">Gastbuch24.de</a></font> ");
document.writeln("</div>      </td>    </tr>  </table>");
document.writeln("</form>");