如何在电子邮件正文消息中显示电子邮件表单的复选框？

<form action="提交表单的URL" method="POST">
  <label for="checkbox1">
    <input type="checkbox" id="checkbox1" name="checkbox1" value="选项1">
    选项1
  </label>
  <br>
  <label for="checkbox2">
    <input type="checkbox" id="checkbox2" name="checkbox2" value="选项2">
    选项2
  </label>
  <br>
  <label for="checkbox3">
    <input type="checkbox" id="checkbox3" name="checkbox3" value="选项3">
    选项3
  </label>
  <br>
  <input type="submit" value="提交">
</form>