The purpose of these rules is to maintain the safety, security, and discipline of adult prison facilities operated under the jurisdiction of the department of corrections in accordance with Title 72 RCW et al., by establishing guidelines for the development of departmental and institution level policies and rules governing the receipt and sending of mail by incarcerated individuals, herein after referred to as "individual" or "individuals," to prevent the transmission of illegal items or contraband into or out of an institution. These rules shall not apply to work release facilities under the jurisdiction of the department.