With presence on about 450 million desktops, Microsoft Outlook is by far the most widely used email application in the world, but it's not popular with everyone.

Some small business owners feel they don't have the skills to administer support for Outlook. IT managers at mid-size businesses may fear it will be more susceptible to viruses and worms than other programs. Still others "just don't like Microsoft," says Erica Driver, principal analyst with Forrester Research, of Cambridge, Mass.

Price comparison

Price may also be an issue for some, though Microsoft's email offering appears to be competitive with most of its competitors.

An average cost for Outlook is hard to pin down. The Standard Edition of Exchange Server 2007 (Outlook is Microsoft's desktop application; Exchange runs on servers) retails for $699. Customers also have to buy client access licenses, which are $67 per user. Customers can also pay $25 per user to get additional features and software assurance. But those who buy five or more licenses at a time get a 25 percent discount and there are more bulk discounts beyond that. To confuse things further, most of the time Outlook is bundled in Office, Microsoft's desktop product suite, as well. Office Basic starts at $129 per user.

Driver says she's done the math and that running Microsoft's email programs using Microsoft back-end software amounts to $100 per user, while Novell GroupWise is $130 per user and Sun Java Enterprise System costs $140 per employee per year. IBM's Lotus Domino Messaging Express is $99, she says.

Email penetration and security

While no one tracks email penetration among small businesses, the picture on the consumer side is one of complete domination by Microsoft. At retail, Microsoft has 99.98 percent of the email software market, according to the NPD Group, a Port Washington, N.Y. market research firm.

For businesses, Microsoft's lead isn't quite as commanding. Driver says no one has a majority of the market, which is split on the server side between Microsoft IBM, Sun and Novell.

Leilani Quiles, IT director for Tew Cardenas, a 130-person law firm in Miami, is a fan of GroupWise. When Quiles started at her job seven years ago, the firm was already using the program. "Every so often the subject comes up to explore Exchange or Outlook," Quiles says. But the consensus is that employees like the calendaring function too much. Quiles also thinks GroupWise is more secure.

That contention comes from a similar argument to Apple's when its operating system is compared to Microsoft's: Because GroupWise and other email programs command a smaller share of the market, they represent a less juicy target for makers of viruses.

He says, she says

Not surprisingly, Microsoft considers such claims bunk. Jessica Arnold, product manager for Outlook, points out that the latest version of Outlook, Outlook 2007, has stepped up calendar functions (users can even publish their calendars on Office Online to let others collaborate on scheduling) and anti-phishing features. She adds that Microsoft is well aware of virus threats and makes use of beta testing to make Outlook more bulletproof.

"Obviously, there will always be people who want to create viruses targeted at different programs," Arnold says. "I wouldn¹t say Microsoft is alone in that."

So why go with one of the competitors? Phil Karren, product manager for GroupWise, says Novell's system is easier to use, cheaper and more secure than Exchange. "What we see is I have some customers with 700 users and there's one IT guy managing it all," he says. Karren says another benefit is that GroupWise "tends to be a lot more frugal with the hardware." That means that it works better with older systems than Exchange.