Now admittedly, this has never, ever occurred to me. It's just not something I ever encountered in my years on this rock.
But when I saw it on Reddit (YSK aka The You Should Know page), and then again on the Today show site, it made absolute sense. Have you ever seen a seemingly random dryer sheet in your mailbox? If you have, you should leave it alone. They were placed there deliberately and for a great reason! According to the Reddit post, your mail carrier may put a dryer sheet in your mailbox to fight against pesky, stinging bugs! Especially if you're out in the county, your poor mail carrier may be fighting off wasps, yellow jackets, hornets, etc, just living in/hiding in your mail box. The boxes make a nice place to hide when it gets cold at night for them. Anyway, the post was done by a mail carrier, and here's what he said: