Cal. Unemp. Ins. Code § 2606.4

Notwithstanding Section 632, “employment” for purposes of this part also means service performed as a clerk-carrier in the employ of the United States Postal Service, to the extent Congress permits this part to be applicable to the postal service, and if Congress permits the states to require the postal service to withhold workers’ contributions and to transmit those contributions into a state fund for unemployment compensation disability benefits.