Tutanota is a free and open source web-mail client that focuses on privacy and security. It has open source iOS and an Android apps. The Android app is published on F-Droid (which means the app does not use Google's push notification system) making it a great option if you want to de-Google your life. All data is stored encrypted and can not be searched, i.e. for commercial use. It offers dead easy end-to-end encryption.
1 GB of storage is free for everyone.
Easy - one password for everything
Tutanota wants to provide the easiest-to-use and most secure email client. You do not have to fiddle with multiple passwords for signing in and for encryption/decryption. The state-of-the-art encryption technology handles all the encryption and decryption complexities. Still: Your password only belongs to you. It is being hashed and salted locally before being transmitted to the servers.
Only you with your password have access to your encrypted data, profiling is impossible. Tutanota combines security with ease-of-use so that everybody can use end-to-end encryption. Now you can take back your privacy easily!