Why encrypt emails?
Do you want to send your digital letters as post cards? Probably not.
Sending unencrypted emails is like sending post cards – anyone and any system that process your mails can read its content. If you encrypt your emails, you put your message into an envelope that only the recipient of the email can open.
What is Enigmail?
Enigmail is a seamlessly integrated security add-on for Mozilla Thunderbird. It allows you to use OpenPGP to encrypt and digitally sign your emails and to decrypt and verify messages you receive.