I have never received any "lottery scams" via my post office.
It's a famous method and was very popular 10-15 years back no matter the country. You could receive once per month and a lot of people failed in the trap. Usually senior people, unfortunately. Nowadays it's very less popular but instead, they call you at home directly, I received such calls sometimes 3 times per week. And when it wasn't a lottery it was because I won a dinner in a fancy restaurant