Even if you don't change anything about it, it'll still be better than any email app/site that's available now in 2025.
It was a mistake to kill the app.
Make it independent like Protonmail, i.e. not reliant on Gmail.
Steve Jobs said you are just a feature. Even in 2025, he is still right.
Email is not going anywhere. It's time for Dropbox's solution to it. And trying to kill it was not the solution.