Cerberus Helpdesk handles mission critical e-mail management for over 4,000 companies worldwide -- from one-person startups to Fortune 500 giants.

Cerberus delivers a highly-customizable, intuitive interface packed with an abundance of powerful features, such as: an exceptionally adaptive anti-spam system, comprehensive search and customer history functionality, e-mail templates for standard responses and canned text, an extensive reporting system, a central knowledgebase providing solutions to previously addressed issues, multiple department and e-mail address support, project and task tracking and emerging automated agent behavior.

Exim is an open source mail transfer agent (MTA), developed at the University of Cambridge for use on Unix systems connected to the Internet.

Exim is a program responsible for receiving, routing, and delivering e-mail messages. Its functionalities are similar like an Internet mailer, or a mail server program. It receives e-mail messages and recipient addresses from local users and remote hosts, performs alias creation, forwards functions, and delivers the messages to their destinations.

Sylpheed is an e-mail client and newsreader software, based on GTK+ GUI toolkit. This free software solution is distributed under GNU GPL and runs on UNIX, Linux as well as X Windows System.

Sylpheed was developed aiming the following:

Sendmail is an open source Mail Transfer Agent (MTA). It is a computer program that delivers mail from one machine to another.

Originally, Sendmail was written by Eric Allman in 1980s. In 1983, Sendmail was first shipped with BSD 4.1, the first BSD version that includes TCP/IP. The current version of Sendmail is 8.13.4, which has been released on March 27, 2005.

Open WebMail is an open source webmail system designed to manage very large mail folders and files in an efficient way. This system is based on the neomail version 1.14 of Ernie Miller.

Open WebMail is simple and easy-to-use software along with a large number of features for its users. This software is considered as one of the major competitors of Microsoft Outlook.

Mutt is a text-based MIME mail client. It was originally written by Michael Elkins. However, it is now managed by the Mutt development mailing list.

Initially, Mutt’s interface was based on ELM client. Subsequently, as development work progressed, features of PINE and MUSH were also incorporated into Mutt. The current version of Mutt looks like SLRN news client.

MailScanner is a highly respected open source e-mail security system providing virus scanner, vulnerability protector and spam tagger.

MailScanner is a generic scanner intending to drive a spam filter and virus scanner and used by MTAs. This software is written in Perl and works well with SendMail and Exim.

Mailman is an open source software for managing electronic mailing system, e-discussion and e-newsletters. This software can be installed on any website that supports CGI scripts.

Mailman is developed by Barry Warsaw and is being used in various forms since its inception in 1997. The quality of the software is being enhanced by years of modifications, tuning and additions. Since 1997, Mailman has been downloaded by more than 35000 times because of its reliable, robust and stable e-mail service.