A mail carrier in Brooklyn stashed about 17,000 pieces of undelivered mail for more than a decade because he was “overwhelmed” by the amount he had to deliver, the authorities said.

The carrier, Aleksey Germash, told investigators he “made sure to deliver the important mail,” according to a complaint filed in federal court.

Mr. Germash, a Postal Service employee for more than 16 years, was charged with detaining and delaying mail on Thursday.

The service’s Office of Inspector General received a tip this month about a Nissan Pathfinder parked in Brooklyn with mailbags stuffed inside. When Postal Service agents visited the location, they found 20 blue post office bags packed with undelivered mail inside the vehicle.