要通过图像实现您所需要的效果,只需进行一个小修复即可。
<!-- ... [earlier code] ... -->
<table align="center" border="0" cellpadding="0" cellspacing="0" class="container h-auto" height="300" width="600">
<tr>
<td align="center" valign="middle"> <!-- valign="middle" added here -->
<!--LEFT-->
<table align="left" border="0" cellpadding="0" cellspacing="0" class="container" width="300">
<tr>
<td align="center" valign="middle" width="100%"> <!-- valign="middle" added here -->
<a alias="Body-Image" conversion="false" data-linkto="https://" href="[link goes here]" style="color: #000000; font-family: sans-serif;text-align: center; text-decoration: none; display: block;">
<img alt="[add alt text here]" class="content-image" src="https://dummyimage.com/300x100" style="display: block;width:100%" width="300">
</a>
</td>
</tr>
</table>
<!--//LEFT-->
<!-- [rest of your code] ... -->
</td>
</tr>
</table>
<!-- ... [later code] ... -->