I use an email address that ends in .io and the amount of people that still ask me ".io? are you sure that's correct?" never ceases to amaze me.
Hell, booking.com will even tell you that "your address looks incorrect" (sometimes, I got it once out of two bookings made on a single day), if you dare to use your own domain .com. They used to nag me about "ohh, are you sure it's not [email protected]"? And I'm not sure what's worse.
It does work well. I used a customized version of https://github.com/mailcheck/mailcheck on an ecomm website and the amount of bounces due to typos went way down.
It is important to tune it a bit based on what you see after installing it to reduce the amount of bad suggestions.