Very much so, and both the Post Office and the US military were very proud to do so.
In a very important scene in the movie Battle of the Bulge (1965), “(Col.) Hessler, after presenting General Kohler a (captured) fresh cake which was baked in the United States, argues that capturing (an important city) will severely damage American morale: if the Americans have the fuel and aircraft to fly things as trivial as cake to the front, such an overwhelming defeat may force them to reconsider their chances of winning the war.”
However, just the opposite was true, that since the Americans had the fuel and aircraft to fly things as trivial as cake to the front, their logistical abilities were downright frightening.
The real German tank commander, Col. Joachim Peiper, on whom Hessler was based, would never have made that mistake.
I always understood that to be sarcasm.