Security for the emails are the most important thing nowadays, in order to assure the protection. cpanel provides you the mail protection.
The feature called Email encryption is to protect your messages from reaching unwanted recipients. When a message is encrypted, the recipient needs the key to decrypt the message. Otherwise, the message will not be readable to the user.
Steps to follow:
1) Login to the cpanel
2) Under Emails, click encryption
3) Fill the details and then give generate key
4) Then save the generated key.
5) After that give import key , give the generated key in the text box.
6) Then click save .
By this way we can encrypt the emails.