On his first morning of retirement, Edwin Marsh swept the old Hollowbrook post office one last time. Behind a coat rack he found a brass mail slot in a wall that never had one. The little plate read TOMORROW'S DEPARTURES. As a joke, he scribbled a grocery list and fed it in. By noon, the milk he'd written down sat on his porch, in a glass bottle stamped with tomorrow's date.

Edwin got greedy. If the slot could send a grocery list to tomorrow, maybe it could send a real message. He wrote a note to himself: 'Edwin, don't sell the house. Trust me.' His hand hovered over the slot.

Edwin shoved the note in before he could change his mind. The slot clicked. A second later, a reply slid out in his own handwriting: 'Too late. You already did. Fix it.' Edwin stared at words he hadn't written yet, his heart pounding.

Edwin raced to the realtor's office and tore up the sale papers just as the buyer arrived. He kept the house, and the post office building with it. Years later, the brass slot still sat behind the coat rack, ready for the next person who needed a letter from tomorrow.