Originals of emails are generally just bits of magnetized iron on a hard drive somewhere. Each printed copy is just that, a copy. For that matter, so is the electronic version at the recipient's end.
Now, if the emails were encrypted, or just signed, that's another matter. Such electronic signatures count the same as physical signatures, But you have to have an electronic copy of the email. Which Corsi could have, on a thumb drive, CD-ROM, or other media. I hope he does.
They snuck them out under their clothes. Printed on paper.