How can I prevent Mailpoet to translate the backend UI

I freshly installed Mailpoet on a German website. Unfortunately the backend UI now is also German. The adminstrator’s language is set to english and the whole WordPress backend is displayed correctly in English – except of Mailpoet, which displays all texts in German. How can I prevent Mailpoet from translating the backend UI?

The page I need help with: [log in to see the link]