https://techcrunch.com/2019/04/01/gmail-turns-15-gets-smart-compose-improvements-and-email-scheduling/

Exactly fifteen years ago, Google decided to confuse everybody by launching its long-awaited web-based email client on April 1. This definitely wasn’t a joke, though, and Gmail went on to become one of Google’s most successful products. Today, to celebrate its fifteenth birthday (and maybe make you forget about today’s final demise of Inbox and tomorrow’s shutdown of Google+), the Gmail team announced a couple of a new and useful Gmail features, including improvements to Smart Compose and the ability to schedule emails to be sent in the future.

Smart Compose, which tries to autocomplete your emails as you type them, will now be able to adapt to the way you write the greetings in your emails. If you prefer ‘Hey’ over ‘Hi,’ then Smart Compose will learn that. If you often fret over which subject to use for your emails, then there’s some relief here for you, too, because Smart Compose can now suggest a subject line based on the content of your email.