Postal Box

We have to go a long way from the house to get our mail.  However, the postal boxes are close to the entrance to the park.  So Barb can pick up the mail every day on the way home from pickle ball.  The first time she went to the mail box, she didn't know which one was ours and there are hundreds of boxes there.  She asked someone there how she could find out which box was ours.  The person said she could ask the mail man inside the building.  So she knocked on the door of the building just as she noticed a sign that said "Do not knock".  The man inside said he didn't know which box was hers because she wasn't on his route but he said he could help her by knocking on the door of her box from the inside.  Then Barb found her box by following his knocks.  She used her key to open the mailbox and saw the mailman's head on the inside of the building looking out and smiling.