Enigmail is a security extension to Mozilla Thunderbird and SeaMonkey. It enables you to write and receive email messages signed and/or encrypted with the OpenPGP standard. Sending and receiving encrypted and digitally signed email is simple using Enigmail. When starting it for the first time, you are guided through the basic setup. We also prepared a new users guide that explains how to use OpenPGP. Features List

Tightly integrated suport for OpenPGP with the Mozilla Thunderbird and Mozilla Seamonkey mail clients Encrypt/sign mail when sending, decrypt/authenticate received mail Support for inline-PGP (RFC 4880) and PGP/MIME (RFC 3156) Per-Identity based encryption and signing defaults Per-Recipient rules for automated key selection, and enabling/disabling encryption and signing OpenPGP key management user interface Automatically encrypt or sign attachments for inline PGP messages Powerful GUI for easy configuration and OpenPGP key management Detailed user preferences for advanced configuration Integrated OpenPGP PhotoID viewer Supports OpenPGP key retrieval via proxy servers Integrates with GnuPG, version 1.4.x and 2.0.x Supports Mozillas Multiple Identities feature Available for: Windows / Mac OSX / Linux x86-32 (all in one official release file), and contributed / distribution builds for other operating systems such as Linux, Solaris, *BSD and OS/2) Many Language Packs, (mostly) included in the official releases, and available separately for localisation of contributed builds