Your Emma emails are optimized to look their best in a person's inbox, but printing is an entirely different matter. There are so many different types of printers and printer settings that it's really not possible to design the emails so that they will print correctly for everyone. In addition to that, the length of your email could very well prevent it from all fitting on a page even in the best-case scenario.
That being said, you can create a PDF of your campaign and print it, if you'd like. Hope this helps!