Section color proportion is odd in the email section. When creating popup design, do care about those details. Nowadays, email subscriptions are giving free material on a subject that they are proficient about. An example would be, cosmology newsletter providing star chart map for available to their subscribers.
However, you are not limited with a star chart! You can create pdf book for tips and tricks in your industry, or even give your thoughts about it. Mobile and Hook CTA(Call-To-Action) are both ok.