Tutanota

Tutanota is a end-to-end encrypted email service that encrypts all data on the device and aims to provide secure electronic communication. This product/service can be a good alternative to mainstream email services for users who are concerned about the privacy and security of their data, and communications.

Tutanota is also open source and codes can be reviewed at Tutanota Github. While it does offer free services which is limited to 1 GB storage space, it also has options for premium and pro paid services with additional features and bigger storage space.

Tutanota can used on browsers and also has apps available for IOS and Android devices. Feel free to browse their website and see what they have to offer to determine if this can become your next secure electronic communications tool.