Updated June 5th, 2019.
If you’ve ever tried inserting a return (or technically, a line feed) in a Messages message on a Mac, you’ve probably not been successful, because pressing the Return key on the keyboard sends the message. (Line feeds in messages on an iPhone or iPad are easy– just press Return, as you’d expect.)
Turns out you can insert a return in a Messages message on a Mac, and as usual, there’s a bit of a trick. Also as usual, it involves the Option key. All you have to do is…
Hold the Option key down as you press Return! That’s it. So now you can write text messages such as the one below.
Tap Return (without the Option key) to send it.