The Drill Instructor might.
Just put it in a plain envelope and decorate the letter. The DI's can't go through your mail, but they will have you open packages in front of them to make sure there is no contraband in there.
We never got yelled at for our mail. If the Rank was wrong, we did push-ups.
We also did 10 push-ups for every letter. I didn't mind, it only makes you stronger.