Okla. Admin. Code § 590:10-1-19
The addresses of all OPERS members are confidential and will not be disclosed to any person or entity. Pursuant to Title 74 O.S. Section 935, any statewide organization of state employees with a minimum membership of 1,000 dues-paying members may annually send one general mailing to all retired members of OPERS and shall pay for the total cost. In order to preserve the confidentiality of the addresses and to comply with the provisions, the System shall not provide the list of retiree addresses directly to the organization. At the sole discretion of the System, the System may require the use of a third-party mailing service. Appropriate agreements shall be entered into between OPERS, the statewide organization, and the third-party mailing service to conduct the mailing, with provisions to protect the confidentiality of the addresses and to prohibit furnishing them to any other person or entity. All costs associated with the mailing or services of the third-party mailing service shall be paid entirely by the statewide organization. The organization shall file a copy of any such mailing with the System.
Okla. Admin. Code § 590:10-1-19