I'm not too concerned about these, although no-doubt far too many of them will be "harvested" and returned without the citizen's knowledge, consent, or vote.
What concerns me even more are the thousands, probably millions of fraudulent "mail in" ballots that have already been filled out, heck maybe even counted already, just waiting to be "discovered" on election night or the next day.
Which is exactly the point.
There is no chain-of-custody.
I’ve worked the polls a couple of times. At the end of the day two people from different parties transport the votes the central ballot facility.
There is absolutely no chain-of-custody with mail-in ballots, which should invalidate them immediately.