Alternatives to Microsoft Exchange Server

One of the last areas in which a Microsoft product has yet to be usurped by Open Source software is a replacement for MS Exchange Server. Many businesses use MS Outlook and MS Exchange Server to access email, as well as to provide calendaring, notes, file sharing, and other collaborative functions. General industry complaints about Exchange Server center around scalability, administration (backup and restore in particular), and licensing fees.

A "drop-in" alternative needs to have compatibility with MS Outlook because it's intended to replace Exchange Server in an environment in which there are Microsoft desktops in existence using Outlook. A "work-alike" alternative provides similar features to Exchange Server, but does not offer compatibility with the MS Outlook client itself; the latter is typical of many of the open-ource alternatives.

There are several "drop-in" alternatives, none of which are fully open source because some type of proprietary connector is needed to provide the services to MS Outlook clients (or provide Exchange services to the Linux Evolution client). For Outlook compatibility, the key seems to be the realization of a full, open implementation of MAPI, Microsoft's Messaging Application Program Interface. That goal is going to be difficult to achieve because MAPI is a poorly documented Microsoft protocol. For Linux-only solutions, the missing ingredient for many alternatives is a usable group calendaring/scheduling system similar in function to that provided by Exchange Server/Outlook.

Of course, independent applications for these functions abound in the open-ource world, but one characteristic of "groupware" is its central administration; another is that all components can share information.

The following sections examine several of the available servers, beginning with MS Exchange Server itself and moving toward those applications that have increasing incompatibility with it. None of these servers are provided with Fedora.

Microsoft Exchange Server/Outlook Client

Exchange Server and Outlook seem to be the industry benchmark because of their widespread deployment. They offer a proprietary server providing email, contacts, scheduling, public folders, task lists, journaling, and notes using MS Outlook as the client and MAPI as the API. If you consider what MS Exchange offers as the "full" set of features, no other replacement offers 100% of the features exactly as provided by MS Exchange Server even those considered "drop-in" replacements. The home page for the Microsoft Exchange server is http://www.microsoft.com/exchange/.

CommuniGate Pro

CommuniGate Pro is a proprietary, drop-in alternative to MS Exchange Server, providing, email, webmail, LDAP directories, a web server, file server, contacts, calendaring (third-party), and a list server. The CommuniGate Pro MAPI Connector provides access to the server from MS Outlook and other MAPI-enabled clients. The home page for this server is http://www.stalker.com/.

Samsung Contact (Formerly Known As HP OpenMail)

This is a proprietary, drop-in alternative to MS Exchange Server (and is also used by many Fortune 500 companies). The Samsung Contact server provides what is almost a full replacement for MS Exchange Server and will (once ITEF finishes the open "calendar spec") work with all the more common Linux email clients and web browsers. The home page is http://www.samsungcontact.com/en/.

Bynari

Bynari provides a proprietary group of servers to act as a drop-in replacement for MS Exchange Server for email, calendaring, public folders, scheduling, address book, webmail, and contacts. Although it runs on Linux, it offers no Linux clients and the Connector provides services to MS Outlook only. The home page is http://www.bynari.net/.

SuSE OpenExchange

The SuSE Linux OpenExchange message server is based on Cyrus-imap and Postfix. Most of the server's groupware features are provided by a proprietary web-based groupware server (ComFire). SuSE OpenExchange also uses Apache, OpenLDAP, Samba, and SuSE Linux Enterprise Server 8 to provide public directories, notes, webmail, scheduler, tasks, project management, document management, forums, and bookmarks. Some compatibility with MS Outlook is provided. The home page is http://www.suse.com/en/business/products/openexchange/.

Kroupware

The Kroupware project was begun to provide groupware functions such as email, group calendaring, notes and tasks, but Kroupware was not designed to be a total replacement for MS Exchange Server and Outlook. The result is composed of the Kolab Server and the KDE Kolab Client. The Kolab Server is based on the existing Open Source components of OpenLDAP, Cyrus-imapd, Postfix, and Apache. The KDE Kolab Client uses special versions of KMail, KOrganizer, KAddressBook, and KPilot that can communicate with the Kolab Server. It is necessary to use the Bynari Insight Connector to enable Outlook to communicate with the Kolab Server. The home page is http://www.kroupware.org/.

OpenGroupware (Formerly SKYRiX 4.1)

OpenGroupware (not affiliated with OpenOffice.org) focuses on groupware and collaboration (and does not provide its own mail server). It can replace Comfire in SuSE OpenExchange to save on the licensing cost or be used with a Cyrus-imap mail server and PostgreSQL and FrontBase (no MySQL) for the database. For connectivity to Outlook, OpenGroupware uses the ZideLook MAPI Storage Provider (proprietary, it maps MAPI to WebDAV) and the Open Source WebDAV middleware server ZideStore. ZideStore translates WebDAV requests to calls to OpenGroupware as well as clients such as Evolution and Mozilla. The home page is http://www.opengroupware.org/en/.

phpgroupware

phpgroupware is an open-source application written in PHP (and used with MySQL or postgresql plus a web server and an IMAP mail server). phpgroupware provides a web-based calendar, task list, address book, email, news headlines, and a file manager. Version 1.0 is expected to be released in 2004. The home page is http://www.phpgroupware.org/.

PHProjekt

PHProjekt is open-source software written in PHP (used with MySql, postgresql, Oracle, Informix, or MS-sql). PHProjekt provides calendaring, contact manager, time card system, project management, online chat, threaded discussion forum, trouble ticket system, email, public files, notes bookmarks, voting system, task lists, reminders, site-search, and integration with the PostNuke news site application. It provides no Exchange/Outlook compatibility whatsoever. The home page is http://www.PHProjekt.com/.

IMP/Horde

IMP/Horde is a PHP-based application framework. When combined with an HTTP server (Apache, Microsoft IIS, Netscape) and MySql database, IMP/Horde offers modules that provide webmail, contact manager, calendar, CVS viewer, file manager, time tracking, email filter rules manager, notes, tasks, chat, newsgroups, forms, bug tracking, FAQ repository, and presentations. The home page is http://www.horde.org/.

Conclusion

There are no open-source only alternatives that can provide full Exchange-like services to MS Outlook clients. If you do not have Outlook clients to worry about, OpenGroupware, IMP/Horde and phprojekt look promising. None of them are provided with Fedora.

Relevant Fedora and Linux Commands

You will use the following commands to manage electronic mail in Fedora:

balsa A GNOME mail user agent for X.

biff A console-based mail notification utility.

evolution A comprehensive and capable Ximian GNOME mail PIM for X.

fetchmail A console-based and daemon-mode mail retrieval command for Linux.

fetchmailconf A graphical fetchmail configuration client for X.

kmail A graphical mail user client for KDE and X

korn A biff applet for KDE and X.

mail A console-based mail user agent.

mutt A console-based mail user agent.

sendmail A comprehensive mail transport agent for Unix and Linux.

xbiff A mail notification X client.