Unlike Kerio and Zimbra, which have versions that can run on multiple server platforms, Zarafa is designed for Linux and built to integrate with any LDAP-based directory service, including Active Directory and Open Directory. Zarafa also offers installation flexibility and supports integration with most common Linux mail transfer agents -- think postfix and sendmail -- as well as options for migrating from Exchange or other mail servers that provide IMAP.
As with Zimbra, access from the iPhone and other mobile devices made possible via an additional package called Z-Push . Unlike Zimbra Mobile, Z-Push is a fully open-source solution that can be implemented at no added cost.
Communigate Pro is a full-featured messaging and groupware solution that integrates support for e-mail, instant messaging, centralized contacts, calendar, task management and voice over IP (VoIP) phone services. Much like Kerio, Communigate supports a wide range client protocols for messaging and collaborative tools that can be accessed natively from Outlook, Thunderbird, Apple's Mail and iCal, among others. It also includes both traditional and Flash-based Web interfaces for its various features and offers ActiveSync support for the iPhone and other mobile devices.
Like Kerio and Zimbra, Communigate runs on various platforms including Windows, Unix/Linux, and Mac OS X, and provides integration with Active Directory and LDAP-based directory services environments. Integration with Lotus Notes calendaring is also supported, as are migration processes from Exchange and POP/IMAP mail servers. The goal is to provide a seamless migration process.
Communigate is available in product bundles aimed at everything from small companies to large enterprise customers to ISPs and other service providers . The bundles offer a variety of unified messaging approaches and incorporate anti-spam and anti-virus solutions.