Tutanota!

Tutanota the open source end-to-end encrypted email app. The open source app Tutanota enables you to send end-to-end encrypted emails to anybody with a tip of your finger. The form and manner of this distribution makes it eligible for export under the License Exception ENC Technology Software Unrestricted (TSU) exception (see the BIS Export Administration Regulations, Section 740.13) for both object code and source code.