[zyphlar]

Those are calendar clients. Now ask Mozilla to write a calendaring server that syncs with every mobile device on the market across 150 calendars some of which have many thousands of appointments each (with years of exceptions to recurrence) -- no mistakes allowed. Also meeting invitations.

This one issue might be what keeps Microsoft in the game.

[cookiecaper]

As usual, Microsoft's wide compatibility is less a function of their effort and more a function of their marketshare; if your stuff doesn't work on Windows, you break it until it does because if you don't work with Windows/Outlook/MS, you're locking yourself out of 90%+ of the market. Hence, MS is always the standard unless you don't care about that market, and there aren't many for-profit companies willing to forgo such a large base of potential customers.

[joubert]

Uhm, there are Exchange clients for iOS, Android, OS X, and I if I wasn't lazy, would Google to see if there are clients for Linux.

[cookiecaper]

Right, that's my point. I mentioned Windows, but I didn't mean to restrict my comments specifically to that (though everything MS does is ultimately a play to further entrench Windows and/or Office, including Exchange, IE, and .NET). MS has other properties whose presence is so ubiquitous that no person attempting to make money off of the market where they dominate can seriously consider leaving them out.

Everyone works with Exchange because Exchange is the de-facto standard calendaring and email server. Of course, Exchange mainly got to this point through association with Windows and the MS brand.

If you want to do something with email or scheduling for users who work at a company with > 100 people, you're almost definitely going to need Exchange compatibility, and there's a pretty good chance you'll run into Exchange in smaller groups too.

The ubiquity of Exchange, Office, and Windows make not supporting any of these infeasible unless your primary motive is not maximum profitability and/or wide impact. For most companies, maximum profitability and wide impact are the primary reasons to continue business. Ergo, support for Microsoft's mainstay suites is a forgone conclusion.

It's a chicken-and-egg problem, as they say. Until we can get business people off of Windows and Office, we are stuck. If Linux vendors were smart they'd target the business workstation with at least as much enthusiasm as they target servers or consumer workstations.

[mryall]

Actually, Apple makes an iCal server:

http://www.apple.com/server/macosx/features/ical-server.html

And Novell GroupWise is the server-side product from that company which does calendaring:

http://www.novell.com/products/groupwise/features/#calendar

There are definitely alternatives, depending on what functionality you need.

[hm2k]

I also forgot to mention Yahoo! who bought Zimbra, which pretty much covers what you just mentioned through and through.

Also see: http://alternativeto.net/software/microsoft-exchange-server/