Don't. Your plain text email is going to render like shit in any modern mail client, and you are going to look like fool who can't write an email. You should a

Don't. Your plain text email is going to render like shit in any modern mail client, and you are going to look like fool who can't write an email. You should actually try this if you use plain text email - email yourself and try and read it in a normal mail client (gmail, outlook, etc) on a phone. You'll need to scroll horizontally to read the message. Now read it on a normal desktop email client. You'll see a skinny tall column of text in a tiny font. Now reply to a normal html email thread and view it in a normal mail client. Congrats - you've just broken the formatting for everyone* on the thread. Nobody wants you see those >> things all over the place. I don't know why this idea persists. Nobody wants to read a book in a fixed width font, nobody wants to read a web page in a fixed width font that doesn't adapt to your viewport size, etc. Hell, programmers even want colors and fancy formatting in their source code. Plain text email is the ham radio of the internet. If you are an email hobbiest and you enjoy sending and receiving plain text emails to other hobbiests more power to you. But don't try and setup a meeting at work over your ham radio. You'll just look dumb.