a friendly mail carrier carefully slides colorful envelopes through a rectangular metal slot built into the front door. The mail carrier holds several letters in one hand while pushing them through the opening with the other. The letters disappear through the slot and fall to the floor inside the house. A curious cat on the other side of the door watches the mail drop down and land on the welcome mat. A homeowner approaches from inside to collect the freshly delivered mail from the floor. a slot in a door through which mail is delivered