Exim is a message transfer agent (MTA) developed at the University of Cambridge for use on Unix systems connected to the Internet. As the SMTP server.
The Courier mail server is a modular multiprotocol mail server that's designed to strike a balance between reasonable performance, flexibility and features. As the POP/IMAP server.
The world's most popular open source database (RDBMS).
Perl 5 is a highly capable, feature-rich programming language with over 24 years of development. Used in XAMS-perl scripts.
The Apache HTTP Server, commonly referred to as Apache is a web server software. Used for the User-Interface.
PHP is a widely-used general-purpose scripting language that is especially suited for Web development and can be embedded into HTML. Used for the User-Interface.
MailScanner is an open source e-mail security system for use on Unix e-mail gateways and was first released in 2001. It protects against viruses and spam. It is distributed under the GNU General Public License.
Roundcube webmail is a browser-based multilingual IMAP client with an application-like user interface. It provides full functionality you expect from an e-mail client, including MIME support, address book, folder manipulation, message searching and spell checking.