GroupOffice is a groupware suite that takes your office online, implementing online collaboration and CRM. It allows you to share projects, calendars, files and email online with co-workers and clients. It is easy to use and fully customizable. It also features synchronization with PDAs and Outlook.
Distributed Checksum Clearinghouse (DCC) is a system of clients and servers that collect and count checksums related to mail messages. The counts can be used by SMTP servers and mail user agents to detect and reject bulk mail. DCC servers can exchange common checksums. The checksums include values that are "fuzzy", or constant across common variations in bulk messages.
The GNU Gatekeeper is a free H.323 gatekeeper based on the OpenH323 project. You can use it to manage a Voice-over-IP network and let endpoints (e.g., Netmeeting) communicate through symbolic names. It also has an external interface for billing and other applications. It runs on a number of Unix versions (including Linux and Solaris) and Windows.
Quassel IRC is a modern, cross-platform, distributed IRC client, meaning that one or more clients can attach to and detach from a central core, much like the popular combination of screen and a text-based IRC client, but graphical. In addition to this unique feature, it aims to be a comfortable chatting program.
Freehelpdesk is feature-rich help desk system designed from the ground up to meet the demands of help desk staff and their users. It is a Web-based system that can accept new calls from your users directly into the system. Calls can be tracked and searched to enable faster response times.
dotCMS is a J2EE Web Content Management System (CMS) which includes a number of features which other Open Source CMS solutions do not. It is extremely easy for both users and developers to work with, and any number of new applications can be built within its framework. It features a multi-tenant/virtual hosting form builder, customizable/extensible workflow engine PHP, Groovy, Ruby, and Python scripting support, a full starter site using Responsive Design (Bootstrap framework), including a mobile version, custom content types, files as content, full-text document and metadata indexing, pessimistic content check-in/checkout, site-wide templating, object level permissions, clustering support, widgets and macros, a robust plugin architecture, an easy Windows installer, ElasticSearch for performance and horizontal scalability, an OSGI implementation, Spring 3 MVC Support, enterprise site searches, an accessibility checker in the WYSIWYG, RESTful APIs to access content and widgets, an integrated help system, and more.
PeerProject is a versatile peer-to-peer filesharing client and file manager. It's intuitive and aesthetic while supporting many networks and features, including BitTorrent, G2, Gnutella, eDonkey, DC++, IRC, HTTP/FTP, and more. It's a mainstream fork of Shareaza p2p, for Windows and WINE.
msmtp is an SMTP client with a sendmail compatible interface. It can be used with Mutt and other MUAs. It forwards messages to an SMTP server which does the delivery. Features include various SMTP AUTH methods, TLS/SSL-encrypted connections (including support for client certificates), support for multiple accounts, DSN, and IPv6 support.
mpop is a small, fast, and portable POP3 client. Its features include header-based email filtering (filter junk mail before downloading it), delivery to mbox files, maildir folders, or a mail delivery agent, a very fast POP3 implementation, many authentication methods, and good support for TLS/SSL.
MUSCLE (Multi User Server Client Linking Environment) is an N-way messaging server and networking API. It includes client-side networking APIs for various languages, including C, C++, C#, Delphi, Java, and Python. MUSCLE lets programs communicate over a network via streams of serialized Message objects. The included server program ("muscled") lets its clients message each other and store information in its server-side hierarchical database. The database supports flexible queries via hierarchical wildcarding, and "live" updates via a subscription mechanism.