Secure Email services..2FA with secure mail extension for Gmail works just fine for me.. Besides that we have :

1)Protonmail – opensource end2end Encryption. Secure Datacenter.. 1km beneath solid rocks..Strict Swiss privacy laws. Trusted Encryption Algorithm Aes, RSA along with openPGP..The Android and ios app is good enough and the Web app works fine on chrome for Android and Safari ios…but a little sluggish as compared to the native apps..You have 2 factor authentication and can disable IP logs..Also mailbox encryption..

All user data is protected by the Swiss Federal Data Protection Act (DPA) and the Swiss Federal Data Protection Ordinance (DPO) which offers some of the strongest privacy protection in the world for both individuals and corporations. As ProtonMail is outside of US and EU jurisdiction, only a court order from the Cantonal Court of Geneva or the Swiss Federal Supreme Court can compel us to release the extremely limited user information we have

2)K9 – K-9 Mail is a 100% free and open source email client for Android.Uses GPG & PGP/MIME support using OpenKeychain..Use the Android app along with “OpenKeychain: Easy PGP” to encrypt/decrypt your emails using OpenPGP.

3)Secure Mail Chromewebstore extention for sending encrypted msg’s using Google servers..

SecureGmail encrypts and decrypts emails you send in Gmail. This happens all on your machine, and the unencrypted text never reaches Google servers. This is useful if you don’t want anyone but the intended recipient to ever read your email.

How To Use :

1) Install the extension
2) Refresh Gmail
3) Click on the lock icon next to the compose button
4) Compose your email and send
5) Enter a password, your recipient will need to enter the same password.

2FA is also recommended with Gmail..

Not shared any links.. Sorry just do some googling.. Thanks..