Quick search by citation:

10 U.S. Code § 909a - Art. 109a. Mail matter: wrongful taking, opening, etc.

(a) Taking.—
Any person subject to this chapter who, with the intent to obstruct the correspondence of, or to pry into the business or secrets of, any person or organization, wrongfully takes mail matter before the mail matter is delivered to or received by the addressee shall be punished as a court-martial may direct.
(b) Opening, Secreting, Destroying, Stealing.—
Any person subject to this chapter who wrongfully opens, secretes, destroys, or steals mail matter before the mail matter is delivered to or received by the addressee shall be punished as a court-martial may direct.
Statutory Notes and Related Subsidiaries
Effective Date

Section effective on Jan. 1, 2019, as designated by the President, with implementing regulations and provisions relating to applicability to various situations, see section 5542 of Pub. L. 114–328 and Ex. Ord. No. 13825, set out as notes under section 801 of this title.