This freebie does what it says on the tin: it checks your spelling and grammar for you, within your web browser. Install Microsoft Editor: Spelling & Grammar Checker and it will underline spelling errors or grammar mistakes as you type.
For the most part, this will help with typing email. But it should also red-line any writing errors on other websites, say, as you fill in a web form or write a comment on social media. Whatever errors it detects will have a zigzag underline that you can click for suggested corrections.
Grammarly does a similar job to ME: S&GC, but I find Microsoft’s extension bothers me with fewer ads. If you want to try this out, it’s available for either Microsoft Edge or Google Chrome. Just make sure to click its browser icon after you install, and sign in with your Microsoft account.