Have You Ever Been in Drug Rehab?

i asked a similair question, but i doubt anybody is going to answer it, so im going to rephrase it.

my friend is locked up (court ordered) in the warm springs rehab center of castaic ,ca.

i need to know what i can send him in the mail
like: if i can mention the krew we are in, or if i can send him playboy pics (with parts marked out)

or if they even read/check his mail.

so if you have been or know sum1 who has been in a drug rehab center, do you think you can help me out with what the mail policies were?