RELATED IDEAS
Reusable components for templates
Be able to have reusable components (Eg headers and footers) that can be referenced within templates - so it's easy to maintain a constant look and feel and easy to make one change that will be reflected across all templates.
I just had the experience of adding a footer to about 200 message templates. We needed to make a change to the footer, so now I will have to update 200 messages because the footer needs to change.
Having basic reusable component functionality would really save a lot of user a lot of time and frustration.