I’ve been emailing with a small group of people at another organization about a mutual project. You know how this goes. Many of the messages we pass back and forth contain no content, just acknowledgment: Great! or Thanks or Will do. But the other day, I received an unexpected note from one of my collaborators, Jacob. Perhaps note is not the word—I’d sent an email to the group (“Got it!”), and now, apparently, Jacob had responded by sending all of us a picture of confetti. This wasn’t a reply. It was something else: a reaction. Last October, Google’s Gmail started letting users send emoji reactions to “quickly and creatively acknowledge an email.” That’s what Jacob did: He quickly and creatively informed me that he was in a state of celebration about the fact that I’d understood his prior message. Thus, confetti. I saw this spelled out in my inbox: “???? Jacob reacted to your message.” In other words, I got another email. As a matter of official policy, reactions are supposed to relieve you of …