Internet is giant spider net where the data flow from one point to another from all terminals. There is a great risk that hackers can get in to the mails and take privacy away. One of the most widely used popular e-mail encryption program is Pretty Good Privacy.
What you need to encrypt and decrypt?
Public Key: Sender use this key
Private Key: Receiver Use this key
For windows GunuGP is a open source and is a free tool.
- Install the software
- Create a certificate
- Distribute the certificate to private parties
Here is a whole tutorial from start to end from the publisher.