Officially, there is no support for this so you will not be able to get exactly the same format. However, wrapping your table around a div with class excel-table offers a similar look with the hover effects in Client 2.0, just without the responsive collapsing behaviour. (Note that this is not part of the documented MessageML specification and thus, is subject to breaking in the future).

<div class="excel-table">
  <table>
    <thead>
      <tr><th>ABC</th><th>DEF</th><th>GHI</th></tr>
    </thead>
    <tbody>
      <tr><td>123</td><td>456</td><td>789</td></tr>
      <tr><td>789</td><td>123</td><td>456</td></tr>
      <tr><td>456</td><td>123</td><td>789</td></tr>
    </tbody>
  </table>
</div>