Also its virtually impossible to be smaller than a few hundred mails to gmail a day as a server and not have your mails instantly spamboxed. Yes, i have gone through the laundry lists of things it could be, and stuff i should set up.
If Google wanted true lock-in they could implement a Gmail-only end-to-end encrypted protocol. Ironically, that's the only thing they don't want to do.
[0]: https://techcrunch.com/2018/02/13/amp-for-email-is-a-terribl... [1]: https://www.eff.org/deeplinks/2018/07/between-you-me-and-goo...