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.
The QmailToaster is an RPM-based Qmail distribution for CentOS, Fedora, SuSE, and Mandriva. This system is designed for ease of deployment and includes strong anti-spam systems. This includes support for SRS, SPF, DomainKeys, and virtual hosting on the SMTP side. On the user side, this has a Web-based administration interface and supports POP3, POP3 over SSL, IMAP, and IMAP over SSL.
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.
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.
ZEG, which stands for "Zero Effort Groupware", is a virtual appliance of SOGo intended to provide a complete out-of-the-box testing environment. SOGo is a collaboration suite (or groupware) with speed and scalability in mind. 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 (CalDAV, CardDAV and GroupDAV, vCard, and vCalendar/iCalendar) and thereby enables the use of many clients and the reuse of any existing infrastructure. The appliance is prepared to be imported in VirtualBox but can also used in VMWare.