To me, it points to a mail carrier, one who sees and knows what type lives where, by mail type and maybe yard signs — retiree here, military there. Trump supporter here.
It’s true that mail carriers see a lot. They know which party is sending you appeals for money and they see your lawn signs or flags. If these were military ballots though, it seems to me that there is a special arrangement for delivery of absentee ballots for deployed military . . . I have yet to see a clearly written article on this situation.