How do you align images to both the top and bottom of a td tag?

This is hardly a challenge with css, though how can I pull this off in an HTML email?  The scenario:

The left td column can be of variable length.  The right is most likely much shorter, but I need to have an image aligned to the top and the bottom of the right column which match the length of the left column. (see amazing graphic below).

I can't use colspan or rowspan.  I've tried a variety of nested things, some inline css styles but I'm not coming up with anything...  Does anybody know how to solve this design problem?

| variable          | img    |
| length            |          |
| content          |          |
|                      |  txt    |
|                      |          |
|                      |          |
|                      |  img   |

Join 200,000 companies around the world that use Campaign Monitor to run email marketing campaigns that deliver results for their business.

Get started for free