Enigmail is a data encryption and decryption extension for Mozilla Thunderbird and the SeaMonkey internet suite that provides OpenPGP public key e-mail encryption and signing. Enigmail works under Microsoft Windows, Unix-like, and Mac OS operating systems. The cryptographic functionality is handled by GNU Privacy Guard. Enigmail is not needed for S/MIME e-mail encryption and signing.
Enigmail was first released in 2001 by Ramalingam Saravanan, and since 2003 maintained by Patrick Brunschwig. Both Enigmail and GNU Privacy Guard are free, open-source software.