Dog flap?

Off to Prospect Park to deliver the letter about the 20 mph signs. As I continue on from a student house to the next letterbox, a young lady comes out and puts the letter directly into the (recycling) bin. No chance for anyone else in the household to see it. Nice to see that she believes in true democracy. Working my way back up the other side, I post a letter through a letterbox. My fingers are free as I hear a dog galloping up the hallway. My fingers are free (and thereby safe) as the dog’s head pokes out the catflap.