Mailvelope is for encrypting your e-mail right on the browser
Famously, e-mail is about as secure as a postcard: anybody who has access to a postcard can read what it says, and that’s the same for e-mail.
Encryption for e-mail has existed for a long time, but has generally been hard to use, and impossible when using a web mail provider such as Gmail or Yahoo Mail.
Enter Mailvelope, a browser plugin that lets you encrypt and decrypt mail messages right from the browser, regardless of whether your e-mail provider is in favor or against that idea.
Go to the Mailvelope listing.