Greg,
Thanks for the extra details! I gave it a try as well, and I believe the problem is caused by the extra [
you added to the beginning of the Email subject. You won't be able to use square brackets in shortcode elements, whether the shortcode is handled by Jetpack or another plugin.
If you remove the square bracket from the subject line, the email looks fine:
http://i.wpne.ws/XWKg
Could you give it a try?
Thanks!