Rival research firm Gartner agreed that Exchange 12 will present migration problems. "The change will make the typical Exchange version migration slower and more complex," wrote Matthew Cain and Stephen Kleynhans, both analysts with Gartner. "Enterprises will need to validate their readiness to deploy and support Windows Server 2003 x64 within their production environments."
The largest enterprises are those most likely to move to Exchange 12, added Pawlack, who sees the 64-bit requirement as a barrier to mid- and small-sized firms.
"Only a small subset of the Exchange customer base needs the kind of scalability that 64-bit provides," he said.
"I think Microsoft is creating as many problems as it's solving with Exchange 12. If there was some capability available only in 64-bit, such as a much greater level of security, then that would be an acceptable reason for going solely with 64-bit.
"I don't think this was thought out," he concluded, "and I hope they reconsider."
For other Exchange users, support deadlines are quickly approaching. All support for Exchange 5.5, which harks to 1997, will end on Dec. 31, 2005, according to Microsoft's product lifecycle plans. And Exchange 2000, which debuted in Nov., 2000, will enter extended support Jan. 1, 2006. Once in extended support, customers must pay for all support and non-security-related hotfixes.