Mozilla Thunderbird is a free, open source, cross-platform e-mail and news client developed by the Mozilla Foundation. Thunderbird provides enterprise and government-grade security features such as SSL/TLS connections to IMAP and SMTP servers. It also offers native support for S/MIME secure email (digital signing and message encryption using certificates). Any of these security features can take advantage of smartcards with the installation of additional extensions. Other security features can be added through extensions. For instance, Enigmail offers PGP signing, encryption, and decryption. Optional security protections also include disabling loading of remote images within messages, enabling only specific media types (sanitizer), and disabling JavaScript.