<form name = "mailform" method=post action="mailto:[email protected]">
请选择你要提交的油箱:
<select name="mail" size="1" onchange="submitcheck();">
            <option  value="mailto:[email protected]">Email1</option>
            <option value="mailto:[email protected]">Email2</option>
            <option value="2">2</option>
            <option value="3">3</option>
            <option value="4">4</option>
          </select>
</form><script>
function submitcheck(){
numform.action=numform.mail.value;
numform.submit();
}
</script>