Ex-Googlers resurrect Google Inbox interface as “Shortwave” email
arstechnica.com
arstechnica.com
So many founders have said the same, and ended up selling saying "you can't hold us to what we said X years ago, circumstances are different now".
But good luck. I hope like Fastmail you can build a profitable business that can last decades.
It's better to not get the email in the first place, but scanning the subject lines is a good idea in some organizations/roles/events.