28 CFR 540.22 - Special postal services.
(1) In the event of loss or damage, any claim relative to this matter is made to the U.S. Postal Service, either by the inmate or the recipient. The U.S. Postal Service will only indemnify a piece of insured mail for the actual value of an item, regardless of declared value.
(2) Inmate packages forwarded as a result of institution administration are considered official mail, except as otherwise specified (for example, hobbycraft articles mailed out of the institution). Official mail is not insured. If such an item is subsequently lost or damaged in the mail process the inmate may file a tort claim with the Bureau of Prisons (see part 543, subpart C of this chapter).
(c) Certified mail is sent first class at the inmate's expense.