With electronic surveillance laws in various countries, it has become a lot more popular and of course important to encrypt your traffic. Be it e-mails, surfing or anything else. For security, privacy and/or just plain spite reasons.
Google Chrome Edit
Firefox extension Edit
- Get an email certificate (there are several suppliers, this one is just free)
- It will send you an e-mail with a link to get the actual certificate and from there it's installed into firefox
- Install the Gmail S/MIME firefox extension
The extension should automatically encrypt e-mails, if you have their public certificate and it will automatically save it if you receive a signed e-mail.
You can set it to automatically sign outgoing e-mails and if it's not because you don't trust google, you can re-enable autosave and let it store the e-mails unencrypted.