cadre can't read your mail, they don't care about your mail unless you have a picture you need to turn in -they will ask, you will give. they may or may not ask if anyone has anything funny or interesting, only because everyone wants a good laugh. just because your letter is pink or someone forgot to write basic, no one is going to know except you getting the mail. the only time they touch your mail is when you're out in jacks or something, and all they do is read your name and you get your stack.
so don't stress, just make sure you address the letter to get there, and no pictures.