Newsletter Templates & Footer Changes?

Is there any way to create templates for the newsletter as well as customize the footer?

Creating a template would allow for a static header that would be used in each email sent, avoiding having to recreate that every time.

For the footer, right now I’m getting the below:

image

The unsubscribe link doesn’t work (putting “default” for the domain) and would like to remove the “Sent via ERPNext”. How do you customize this part?