Scalix is a relatively new player that from the get-go targetted the entreprise market early on. It was originally developed on top of HP OpenMail, and was licensed from HP. On top of standard messaging and groupware features it supports a lot of enterprise-grade functionality such as LDAP and AD support, high availability, multi-tenant management, support for Outlook sync and mobile devices, and many others. It features a nice, slick webmail client, but supports Outlook and mobile devices, on top of other open source clients such as Evolution, Thunderbird and many others.

Scalix was recently bought by Xandros and is now offered as a hosted instance, commercial turn-key product or a community-supported downloadable product. Because of its rich features, it should be considered as a contender in any enterprise deployment.

Open-Xchange is a messaging and collaboration server that is OEMed by many service providers because of its rich features, slick webmail client and ease of setup and use. It supports many open standards protocols and supports Outlook sync via a commercial extension. Originally a commercial product that was bundled with Novell’s Linux Messaging product (SuSE Linux Open-Xchange or SLOX), it features messaging, group calendars/addressbook and scheduling, identity management (support for LDAP and AD), document management, portals,  and more.

Recent releases highlight its social networking capabilities with the ability to share information with Social Networking sites like Facebook and LinkedIn. It will also soon feature support for mobile clients via Exchange’s Active Sync technology. The software is available as a community-supported product, a commercially-supported product, a turnkey appliance or as a hosted instance.

Definitely a mature, feature-rich solution that is in many ways a good choice for midsized to large organizations. Should be in the evaluation shortlist if you are looking for a messaging and collaboration platform for your organization.