How to use preview-email or something similar in e2e tests?

I have an angular frontend with an express backend. My app is heavily dependent on using email because of write restrictions on the database. I'm writing some e2e specs, in which I would like to include the the email previews generated by preview-email.

The problem is that the email previews do not open in the automated chrome window, but in a seperate 'normal' window. I figure this is a core part of how opn works, which is what preview-email uses to open the emails. Is there a way to have the preview emails open in the automated window, or another way to test the generated emails in e2e specs?