Encryption may sound like a subject best left to hackers and tinfoil hat wearers, but don’t be fooled: It’s a critical part of contemporary life and something that’s important for everyone. Google’s standard method of Gmail encryption is something called Transport Layer Security. The only way to get that level of protection in Gmail right now is to rely on a third-party service such as FlowCrypt, available as a Chrome or Firefox extension on the desktop and as its own mail client for Android.”]
Source: https://www.computerworld.com/article/3322497/gmail-encryption.html