Making a copy of your email is as easy as 1, 2, 3.
1 - Click on the Messages tab in the upper left hand corner of your account
2 - Click the box directly to the left of the email you wish to copy
3 - Click the Copy button in the upper right hand corner of your screen. You're all done!
We'll name it Copy of - whatever it was called originally, but you can change it by following these steps.