And that's why services like Tutanota (https://tutanota.com/) and Proton Mail (http://protonmail.com/) offer the option to send password protected / encrypted email to third-party. This can be used to prevent Google or Microsoft from spying on your emails as the actual email is never sent to their server. Yes, sharing passwords beforehand can be a pain. But even if you SMS / message them the password, or just put hint to it in the subject - "the pass is your phone number" or "the pass is your fathers name" - it still creates an additional barrier for Google or Microsoft bots to index your email. While we may not be able to do this for every email, we certainly can do this for personal emails. This process also creates awareness in your social network, when they ask you why you are using such convoluted methods to send them email.