How about this?

https://i.imgur.com/g0BzQ2q.png

Sapling - https://sapling.ai - has created a neural-net based grammar checker that doesn't generate any suggestions based on rules or if-statements. It's backed by millions of real English sentences. The result is a spell checker that behaves a little more like a human. No guarantees on correcting everything all the time, but with people writing and more data it's getting better every day. We've found it generates very few false positives and more suggestions than other spelling and grammar checkers.

Traditional spell checkers will look up spelling based on algorithms that look for edit-distance, or perhaps from a database of common misspellings. If you make too many character perturbations, or if the example isn't in the lookup table, there will not be a match.

Disclosure: I'm part of the team at Sapling Intelligence. I'd love for you to check it out and play with it, in whatever contrived setting you want, but also just let it be your background personal copy-editor for emails. Let me know what you think!