These are just some general mail guidelines.Each prison has an operating procedure for mail so some things may vary from prison to prison

Thanks to Sgt.A for pointing me in the right direction!

3138. General Mail Regulations.
(a) All nonconfidential inmate mail is subject to being read in its entirety
or in part by designated employees of the facility before it is mailed for or
delivered to an inmate. The institutional head or designee may reject mail
sent by or to an inmate as provided in section 3136.
(b) All incoming packages and mail addressed to an inmate shall be
opened and inspected before delivery to the inmate. The purpose of
inspection shall be to receive or receipt any funds enclosed for deposit to
the inmate's trust account; to verify and record the receipt of permitted
personal property; and to prevent the introduction of contraband.
(c) Outgoing inmate mail shall be inspected in accordance with local
procedures.
(1) All outgoing packages shall undergo inspection by appropriate
employees before the package is sealed and mailed.
(2) No collect-on-delivery packages or letters of any kind shall be
accepted for an inmate.
(d) Packages.
(1) Facilities will establish and make available to all inmates procedures
for the receipt of packages from their correspondents in accordance with
limits set for their assigned inmate work/training incentive group. Such
procedures may require an inmate to obtain prior approval to receive a
package. Facilities may refuse to accept packages addressed to an inmate
if prior approval has not been obtained, or if a package is received at a
facility, the facility may refuse to deliver the package to the inmate and
dispose of the package as provided in subsection 3147(a)(6) without the
need to hold the package pending appeal as provided in subsection
3147(a)(5)(B).
(2) Facilities will establish and make available to all inmates procedures
for shipping packages to their correspondents.
(e) Enclosed Funds. Funds may be mailed to an inmate by money orders,
certified or personal checks, or any other negotiable means except cash.
Funds received in the form of a personal check will not be released for
spending by the inmate until the check has cleared the named bank.
(f) Publications.
(1) Publications are reproduced, handwritten, typed/printed, and/or
pictorial materials including books, periodicals, newspapers, and
pamphlets. Inmates may subscribe to newspapers, periodicals, and 3138. General Mail Regulations.
(2) Publications must be addressed to an individual inmate except for
donations to the institution as otherwise permitted by these regulations and
local procedures.
(3) A publication received through the U.S. mail from the publisher or
bookstore shall be excluded for the reasons stated in section 3006(c).
(4) Nothing in this section shall be construed as limiting a facility's right
to inspect nonconfidential material and to limit the number of publications
an inmate may possess at one time.