I just wanted to add a relevant personal anecdote. I've recently moved and registered in another county. My state is one of those that decided to send everybody a mailin ballot. I never check my mailbox so the ballot from my current county might still be sitting in there. All I know is I still ended up getting a ballot from my previous county. Theres absolutely no safeguards for the mailin ballots. Anyone from your kid to some organization can fill it out and drop it in a random box they have scattered around and there is really no way to tell, I mean I guess they can tell if the voter the ballot is supposed to be for complains or tries to vote but if you're one of the many people who don't vote? I don't see how they'd detect that. Also somebody could possibly fill out or tamper with the other ballot I never bothered to check on.