While these functional gaps shouldn't automatically disqualify Gmail, IT managers should carefully consider them while making a decision, Cain and Austin said.

In an interview last week, Eron Kelly, senior director of the Microsoft Business Online Services Group, said Microsoft expected Exchange users to be dissatisfied with the feature gap when using Outlook with Gmail.

"This will just further reinforce in the eyes of customers and users that the Outlook experience is best fully replicated feature by feature in Exchange," Kelly said.

Kelly invited Google to consider becoming a hosted Exchange provider in order to get around the feature-gap issue. "We'd be happy to help Google do that. We have a great partner program."

Regarding the view that Google is increasing its competitive pressure on Outlook and Exchange, Kelly noted that Google is but the latest vendor in recent years to support Outlook connectivity, joining Novell, IBM, Oracle and Sun, among others.

"This is Google falling in line with the general trend of the industry," he said. "This is an example of further reinforcement that the Outlook experience is the premier and preferred experience for e-mail users."

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