Cemaphore, which was founded in 2002, is no fresh start-up. According to Pike, the company already has about 100 corporate customers and 70,000 licensed seats for a non-Google MailShadow product that can be used to replicate Exchange messages for business continuity purposes and during upgrades from one version of Exchange Server to another.

But being in beta, MailShadowG isn't perfect. For example, some testers with large Exchange e-mail boxes have had problems during the initial upload of their directories into Gmail, Pike said, although he blamed that on Google. "Their view is this could be a spam or denial-of-service attack," he explained. "So they throttle you down." Subsequent synchronizations shouldn't suffer from that problem, Pike added.

Where's all my contact info?

The bigger problem is how to preserve Outlook and Exchange data as it is imported into Gmail. Created in an era when spreadsheets were still king, Outlook uses copious hard-coded data fields. Gmail, by contrast, was developed after the rise of search engines. Google's software has far fewer structured fields because it assumes that "if you need to find something, you're going to search for it, not do a column sort," Pike said.

For instance, Outlook uses first and last name fields, while Gmail just has one field for both. Or take the recurring meetings function -- Pike said Gmail has "very limited" support for that compared to the combination of Exchange and Outlook.

Such differences are big enough that they pose some problems for MailShadowG, he admitted. "For the things that really matter, we do 95 per cent well," Pike said. "But this isn't a 1:1 solution."

Pike claimed that data will never simply be "obliterated" by MailShadowG during the import process. If the software can't find an equivalent field in Gmail for one in Outlook and Exchange, it will move data to a general notes field, he said. Pike also expects Google to partly fix the problem by eventually letting Gmail users create their own data fields.

Still, data fidelity is a big enough issue at this point that Pike himself isn't pushing MailShadowG as a way to help Gmail replace Exchange, but instead to help it back up the Microsoft technology. "We've told people that you really have to think of this as a continuity solution," he said. "If you're going to make a full migration, you're going to need to run the two in parallel for a long time."

Gartner analyst Matt Cain agrees. "I don't think that in this case Outlook would be the front end of Gmail," Cain said via e-mail. But he does expect MailShadowG to catch on among individual employees seeking a way to back up their Exchange work e-mail and contacts, even if their companies frown on that information "being stored outside the official e-mail system."

Pike sees another, and bigger, reason why Gmail won't be replacing Exchange at the e-mail back end anytime soon: its still-spotty support for BlackBerry devices, Windows Mobile smart phones and Apple Inc.'s iPhone. "Google's BlackBerry sync is not an enterprise product," he said flatly.

MailShadowG doesn't support smart phone synchronization yet, either, although Pike said that he is "very interested in providing" it if Google doesn't step up to the plate.