Fixing DOuble CApitals as you type20 Jul 2015, by Artur Malabarba.
This is something that’s bothered me for a very long time. My pinky is slow when it comes to releasing the Shift key, and frequently leads to typos. MOst typos (hitting letters in the wrong order) are already covered by auto-correction, but there’s another common typo that it doesn’t fix. EVery now and then, I’ll start a sentence with two uppercase letters.
After the billionth time that it happened to me, I finally took the time to write up a question on Emacs.StackExchange. The answers were fast, and so high quality that I don’t even have improvements to suggest. Instead, I’ll just point you straight to Dan's answer, and show how I activate it.