jimmycrow on "Change the CSS in emails Word Press generates to subscribers"

I would like to change the look of these emails that wordpress generates when a customer write a review of an item on my site or comments on a blog post.

currently they look like this...

http://americanresistancegear.com/wp-content/uploads/2013/11/american-resistance.png

I and to add my logo and change the colors to match the site.

Does anyone know how i would go about doing this or where the CSS/HTML for these emails is located?

Thanks - Jimmy