I use Apple Mail v10.3 on a iMac using OS 10.12...

I use Apple Mail v10.3 on a iMac using OS 10.12.6

I have been trying to find a way to quickly add a line in emails as a page or copy break .... without needing to hold down the underscore key. Is there a simple way to do this?

Seems like a basic feature Mail should automatically include.