Enigmail is an extension to the mail client of Mozilla, SeaMonkey, and Mozilla Thunderbird which allows users to access the authentication and encryption features provided by GnuPG.
Main Features:
- Encrypt/sign mail when sending, decrypt/authenticate received mail
- Support for inline-PGP (RFC 2440) and PGP/MIME (RFC 3156)
- Per-Account based encryption and signing defaults
- Per-Recipient rules for automated key selection, and enabling/disabling encryption and signing
- New: OpenPGP key management interface