This time, I made it about 30% of the way through this "quick guide" with a Gmail account. I don't want to have my password in plaintext, so I'm fine typing it in each time to get started, but I never got over the finish line. I got stuck somewhere around minimizing the number of system headers that go out with each message.
Please let me know if anyone has recommendations for a CLI email client that hooks up with Gmail on a modern Linux distro relatively simply.