Widely viewed as synonymous with business-class email and collaboration, Microsoft's Exchange is far from the only fish in the messaging sea. Indeed, despite its clear market dominance, there are still plenty of alternatives, each capable of delivering much the same functionality — to the same clients, including Outlook users and mobile workers with wireless handsets.
These Exchange alternatives exist because they tend to work out cheaper, as well as being easier to both manage and support. At the same time, they deliver similar levels of scalability and robustness as the Microsoft original.
Two obvious candidates are IBM's Lotus Notes and Novell's GroupWise, both long-term thorns in Exchange's side. That said, we haven't included either product in this group test, mainly because they're rarely seen as like-for-like replacements and we're more interested in products designed to do what Exchange does without making it evident that something else is at work on the server.
To this end, we picked five somewhat less obvious alternatives. One (MDaemon Pro) is a fairly typical Windows-only solution, while Kerio Connect and Gordano Messaging Suite (GMS) can be deployed both on Windows and other hosts. We've also included an open-source product (Zarafa) written for Linux and, because of the increasing popularity of hosted services, Google Apps Premier Edition.
Each has its pros, cons and idiosyncrasies, as outlined below and detailed in the individual reviews, while at the same time sharing a common goal: to do what Exchange does, only more cost-effectively.
What we tested: summary of features