How do I set my email to open up in a full window instead of a pop-up window?

[McLemoreAvenue]

Samsung Note 4 - Email links keep opening in pop-up / Multi window.

I activated multi-window on my new Note 4 and I have changed some setting so now when I click on a link in an email, the link opens in a pop-up window instead of in full screen view.

How can I change back to opening in full screen by default?