The SeaMonkey project is a community effort to develop an all-in-one Internet application suite. It contains an Internet browser, email and newsgroup client with an included Web feed reader, HTML editor, IRC chat, and Web development tools, and is sure to appeal to advanced users, Web developers, and corporate users. It uses much of the Mozilla source code powering such successful siblings as Firefox, Thunderbird, Camino, Sunbird, and Miro.
phpGroupWare (formerly known as webdistro) is a multi-user groupware suite written in PHP. Its provides a Web-based calendar, todo-list, addressbook, email, news headlines, and a file manager. The calendar supports repeating events. The email system supports inline graphics and file attachments. The system as a whole supports user preferences, themes, user permissions, multi-language support, an advanced API, and user groups.
PHPwebmail is a Web-based IMAP and SMTP mail client. Often it is not possible to make outside mail connections from networks behind strict firewalls, or to configure a regular mail client (for example in an Internet cafe). With PHPwebmail a mail client only needs a WWW connection to the mailserver. Specifically it only needs a connection to the webserver hosting PHPwebmail. Most of the times the Web and mail server will be the same machine but PHPwebmail can connect to other mailservers as well as long as an IMAP connection between these two machines is allowed.
OpenGroupware.org is a set of applications for contact, appointment, project, and content management. It is comparable to Exchange and SharePoint. It is accessible using Web interfaces or using local clients via WebDAV, GroupDAV, and CalDAV. Custom applications can be developed using the XML-RPC API. OpenGroupware.org runs on almost every GNU/Linux system.
xP provides an intuitive, high quality, graphical (X11) user interface to the University of Washington's PINE Messaging System. xP aims to provide an interface that is welcoming and easy to use for the new user, while still retaining the look, feel and key commands of PINE for the experienced user.
LibESMTP is a library to manage posting (or submission of) electronic mail using SMTP to a preconfigured Mail Transport Agent (MTA) such as Exim. It may be used as part of a Mail User Agent (MUA) or another program that must be able to post electronic mail but where mail functionality is not the program's primary purpose. LibESMTP is not intended to be used as part of a program that implements a Mail Transport Agent.