Surely the government already knows who is a citizen (otherwise it would not be able to stop noncitizens from registering), so surely it would be trivial for the government to use this list of citizens to send out ballots?
Citizen baby is born? Add them to the list of citizens. Citizen dies? Remove them from the list of citizens. Citizen moves? Have them inform their new municipality about their change of address - which they'll probably need to do anyways for tax and mail reasons.
Citizen baby is born? Add them to the list of citizens. Citizen dies? Remove them from the list of citizens. Citizen moves? Have them inform their new municipality about their change of address - which they'll probably need to do anyways for tax and mail reasons.