Most of us already knew about the MICT (Mail Isolation Control and Tracking) system which is one of several used. Its also easy to extrapolate that they have the ability to see inside envelopes as well because science has been able to see under the paintings of the masters for at least 30 years now.
I figure the feral government will do anything it damn well pleases in regards to any communication, be it electronic, spoken, snail-mail, or whatever. You see, they are willing to kill you for your offering them the slightest bit of resistance to anything they might do. Until we reach the same point, they'll do anything they want.