did you create the checkout pages using the eCart checkout wizard?
look on the confirm page, are there set session value behaviors on that page?
If not, you will need to add them.
on the server behaviors panel, click the plus button. Select eCart -> General -> Set Session Value.
Set the trigger to any form post.
for the value, click the lightning bolt and select one of the shipping form elements. Set the name to use the same name as the form element.
once the confirm page is set to create the session variables, you should use those in the email.