Cloud-based e-mail may be generating powerful market buzz, but in the enterprise, Microsoft Exchange today remains the dominant e-mail platform. However, e-mail, though essential, is difficult and expensive to manage with its increasing storage requirements. So many businesses are now trying to untie e-mail from the rest of IT infrastructure elements such as storage, archiving and disaster recovery products, according to an independent survey by Osterman Research on Microsoft Exchange 2010 migration plans among enterprises with 1,000 or more users.Consequently, making e-mail less dependent on the IT infrastructure will expand what e-mail should include \u2014 and businesses are demanding that e-mail encompass features like archiving and unified communications.All of this sets the tone for the adoption \u2014 or lack thereof \u2014 of Exchange 2010, which has new features that include: built-in e-mail archiving that eliminates for a third-party archiving vendor; the ability to use cheaper storage systems; voicemail and other unified messaging tools rolled into Outlook; and an enhanced user experience in both Outlook and Outlook Web Access.Exchange 2010 has more momentum now than Exchange 2007 had at a similar time in its lifecycle, according to the Osterman Report, which predicts that Exchange will remain the market leader for at least the next several years. [ For complete coverage on Microsoft's SharePoint collaboration software \u2014 including enterprise and cloud adoption trends and previews of SharePoint 2010 \u2014 see CIO.com's SharePoint Bible. ]The Osterman Research survey also reports that 44 percent of respondents say they plan to migrate to the new e-mail platform within the next 18 months, which is unusually high for a new Microsoft product, according to the report.However, migrating to Exchange 2010 will be challenging, confusing or just plain not feasible in a soft economy that has forced companies to cut back or freeze IT budgets, according to the report. As the economy starts to improve, enterprises will have to decide whether they have room in their budgets, or the staff to invest in an Exchange 2010 migration.Here are six reasons driving enterprises to move to Exchange 2010, and six reasons they are putting it off for now, based on the Osterman survey data.Why Exchange 2010 Is Worth ItWhat is driving IT departments to move to Exchgange 2010? Here's what Osterman's survey respondents say:Support for larger mailboxes \u2014 50 percent of respondents said this is driving their decision to move to Exchange 2010. Improvements and flexibility in storage, including storage utilization, footprint and storage options (e.g., Direct Attached Storage) \u2014 50 percent.Improved built-in archiving, retention policies, transport rules and compliance capabilities \u2014 48 percent.Improved Outlook Web Access \u2014 40 percent.Improved high availability and disaster recovery with DAGs (Disaster Availability Groups) \u2014 40 percent.\n\nImproved user productivity features, such as voicemail preview and\nconversation view \u2014 40 percent.Why Exchange 2010 Is Not Worth ItSurvey respondents cited the following as reasons for not planning a migration to Exchange 2010.Overall IT budget prohibits a migration \u2014 57 percent call this an Important or Very Important Reason.\n\nHappy on current non-Microsoft platform \u2014 43 percent.It's too difficult to switch from our non-Microsoft e-mail platform \u2014 31 percent.We have only recently upgraded\/migrated to Exchange 2007 and it's too soon to migrate to Exchange 2010 \u2014 29 percent.\n\nOnly beta backup software available currently \u2014 15 percent.Lacking personnel with technical expertise to architect and manage the new system \u2014 14 percent.Shane O'Neill is a senior writer at CIO.com. Follow him on Twitter at twitter.com\/smoneill. Follow everything from CIO.com on Twitter at twitter.com\/CIOonline.