[imachine1980_]

I don't work in the area of email nor Google but I see two problems.

1) you need to constantly update the spell checker so each time you say this is word or something like that most likely the data is send the problem is part of the data, I assume Google do something similar whit data send to span and mark as not spam. This is full email redirect and analysis not partial like old word processing.

2)I feel ai make this even more harder so now you can't simply check patterns as simply as before, and you need to check the whole content constantly

[_heimdall]

We've had spell/grammar checkers in word processors that worked totally offline for a long time now. They definitely can be improved with a hosted service but that's by no means necessary and comes with tradeoffs like latency and offline support.