On a related thought, using a 'secure' (or so they say ?) email provider à là protonmail is just secure if you send your email to another protonmail user. Problem with services like that is they omit to tell their users that email is not E2E, and sending from protonmail to gmail will just disable the benefits of using protonmail. So yes, if you are trying to send encrypted email to a GMAIL user, your only way is to u…
They hopefully have a good secure authentication system (Protonmail just added SRP and 2Fa) and hopefully have correct policy for things such as DKIM, SPF.
They hopefully also keep up with security updates and stuff like that.
Doing these things seems normal to many, but the reality is that many E-Mail providers have non of those things.