Yep, it makes sense because when you drop something into the box, you can&#x27;t get it back out.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Post_box" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Post_box</a>