Here’s the thing: There once was a time when all you needed was a well-trained carrier pigeon, a tiny scroll, a well-kept coop, and a whole lot of patience to send a message to your friend 1,000 miles away. But one-way messages, limited to roughly the distance between New York City and Florida, are SO far from cutting it today. Jokes aside, our lives are powered by email, and our ability to send a...