Thanks for playing the game. Others have suggested to add bad mails with a different visual to make the game more strategic and make leaderboards to incentive to play and reach high score. Your suggestion comes under this.
As far as I know as a postmaster, they are forbidden from reading the contents of the letter because of privacy and safety reasons. Once again, Thanks for checking it out and for you suggestion. I would be more than happy to listen to more suggestions you might have to fill in what you feel is missing.