How do I compose an email using Emacs' keybindings?

I’m a little nervous that this question is extremely naïve, but I have been continually (every 10 days or so) seeking its answer for months now.

I want to compose emails, preferably to be sent from my Gmail account, using all of the keybindings in Emacs. I do not care about being able to send an email from within Emacs (although I’m not opposed to it) –- I would be happy to be able to write a properly formatted message in Emacs and then copy and paste it into the relevant field of one of Gmail’s "New Message" windows. My problem is that, with respect to typesetting, I do not know how to properly format a message for Gmail.

The reason I want to learn how to do this is simple: when I am composing an email, I am editing text, and when I am editing text, Emacs provides my desired macros and keybindings.