Quoted off http://www.eweek.com/c/a/Data-Storage/Cisco-Buys-PostPath-to-Compete-with-Microsoft-Exchange/
"Cisco Systems acquired PostPath, a Microsoft Exchange e-mail storage competitor, and heads down the path of a big-time "co-opetition" to handle enterprise e-mail against a longtime partner, Microsoft. PostPath uses augmented open-source software and an optional appliance that plugs directly into a data center to offer a lower-cost, in-the-cloud e-mail server alternative to Microsoft Exchange. Exchange has long been known as one of the most complicated business software packages that IT personnel handle."
Nevertheless, if you are looking for a powerful email client/server that brushes shoulders with Exchange, try www.zimbra.com, their web mail is simply magnificent. They have a 100% open source version readily available for download/use.
---Sharing some frustration---
I've been using, consulting on and supporting Exchange for years and up to 2007, its a superb product but you need people with a PhD in Exchange to get it working properly. This is mainly due to complex integration with Active Directory and other Windows components. Exchange 2007 installation takes hours! But once its done, you can go straight down to Powershell and start managing it scriptly...something MS should have thought of and done yeaaaars ago. GUI is great, but lets face it, ..it introduces bulk and possible coding errors etc thus creating a risk to the core functionality of Exchange itself. And what the heck is the deal with the 5 roles, 2 roles i understand, email and voice features, finito, no, here we have 5 roles. Why? To buy more Exchange boxes. Hello Microsoft, hear me, hear me, people are trying to save cost and simplify stuff, why complicate things even more? Oh, wait Sanjay, is scalability, ermm...hey dudes, so you basically kicking Exchange 2003 and its predecessors in their nuts heh? Not scalable issit? Hey, those pre-2007 products are just aye okay....
Sometimes i ask the question, are all the features of Exchange 2007 really necessary? I mean, really, really necessary? Are we at the point of saturated ideas and ideology of innovation? I would love to know how many of us use anything in Exchange except the Email, Contacts and Calendaring as often? You probably answered, hmm..true (if you are not a MS advocate).
I met a friend who works for Microsoft while going for a quick "breather" below the lobby of the Malaysian Twin Towers and i asked her, hey, how's TechED 2008 (i didn't attend..didn't have enough money..:P ) and peculiarly, being in a very strategic and influential front of the company she replied... " What is there to showcase anymore for infrastructure? " I was expecting a chuckle or smile but she starred sharply and confidently at me. And come to think of it, its probably true. I mean, another question i ask you fellow readers, how many features in Active Directory do you actually use/need?
Will Exchange ever be simplified? I hope so...