Thunderbird is a total redesign of the Mozilla mail component to produce a cross-platform, stand-alone mail application using the XUL user interface language. It has many new features, among them the ability to customize your toolbars the way you want them. a new look and feel with a large number of downloadable themes which alter the appearance of the client, and the ability to add UI extensions.
Tine 2.0 is a Web-based groupware solution that focuses on usability and correctness. To achieve these goals, the project uses usability experts and covers most of the code by unit tests. It contains support for contacts, tasks, calendar, email, CRM, VoIP integration, a time tracker, ActiveSync, and a flexible rights management system.
EGroupware is a Web-based groupware suite. It contains many modules, including Calendar (personal calendar and group scheduling, notifications and alarms), Mail (IMAP only), InfoLog (todos, notes, and phone calls linked to contacts/CRM), Contacts (an address book for storing and sharing contact information), ProjectManager, Tracker (bug or incident tracking), TimeSheet, SyncML, CalDAV & CardDAV support, and SiteMgr content management
SOGo is a very fast and scalable modern collaboration suite (or groupware). It offers calendaring, address book management, and a full-featured Webmail client along with resource sharing and permission handling. It also makes use of documented standards (IMAP, CalDAV, CardDAV, etc.) and thereby provides native connectivity (without plugins) to many clients such as Microsoft Outlook, Apple iCal, the iPhone, Mozilla Lightning, and a plethora of mobile devices via SyncML. It can reuse any existing email and database infrastructure, avoiding long hours of site restructuring.
GROUP-E is collaboration software which integrates groupware, project management, and business server on one platform. The solution is based on a LAMP architecture (Linux, Apache, MySQL, PHP). GROUP-E offers project management, transparent Samba (file server) integration, integration of Cyrus IMAP server with administration and personal SIEVE filters, support for SyncML 1.0, LDAP-based user management with single sign-on authentication, and LDAP contact databases. GROUP-E also provides ActiveSync for synchronization.