The PortalSys Addressbook is designed for clients who use Outlook on the desktop but use Linux as the mail system. It allows you to easily integrate Outlook with your Linux system's addresses. The system is made up of two parts: an Outlook service for your Win32 clients and a server-side application to generate and update your addressbook as often as you like.
R-AddressBook is a Java address book which stores its data in XML format. It can be run on virtually any computer (including PDAs) and offers local and global address information storage, WebServices based synchronization, off- and on-line operation, no restriction on the type or number of fields for each entry, and automatic address updates.
Elmtree Express Server is a realistic alternative to the Microsoft Windows server plaftorm. Express Server is a workgroup server solution, providing your business with integrated email, print management, and data storage functionality, all in one easy package. It includes an email server, a central address book via LDAP server, a DHCP server, a central file server, a print server, automated daily backups, GUI administration tools, and more.
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.
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.