javascript 发邮件问题

Question

<script language="javascript">
function sendmail() {
    var msg = document.forms[0].username.value;
    var com = document.forms[0].email;
    var mm;
    for (var i =0;i<com.length;i++) {
        if (true == com[i].checked) {
           mm = com[i].value; 
        }
    }
    var contentm = msg+mm;
    document.forms[0].action = "mailto:"+ contentm;
}
</script>
<table width="640" height="20" border="0" cellpadding="0" cellspacing="0">
  <form action="" enctype="multipart/form-data" name="email" id="email">
    <tr>
      <td width="98" class="url_main">姓名</td>
      <td width="515"><input name="username" type="text" id="username"></td>
    </tr>
    <tr>
      <td class="url_main">邮件</td>
      <td><input name="email" type="radio" value="[email protected]" checked>1
          <input name="email" type="radio" value="[email protected]">2
          <input name="email" type="radio" value="[email protected]">3
          <input name="email" type="radio" value="[email protected]">4
     </td>
    </tr>
    <tr>
      <td colspan="2"><input type="submit" name="Submit" value="Submit" onclick="sendmail();"></td>
    </tr>
  </form>
</table>
记得给分~~~