It's a feature.

Try fastmail for how to build an instant Web interface that is just ridiculously fast. Everything is instant, it has offline support, email address aliases... I dont know. Couldn't be happier. I literally have nothing to complain about at all.

Except yes, it's part of the five eyes countries, which means every email is likely also in nsa datacenters. I dont like that, and would prefer it not to.