I've tried using views, but when I choose the rendered entity display of the MailChimp campaign field, the result is empty even though I've created 3 campaigns from within my Drupal site. I don't think views is the answer anyhow as creating a campaign from a Drupal site still requires logging in to MailChimp to send. So I need to be able to display newsletters created in MailChimp.
I've resorted to displaying the archive of the latest newsletter in an iframe. Besides being unattractive, it requires my client perform extra steps which is counterproductive. Not to mention, it is not responsive.