Mailbox servers will also now be able to fail over to another one within 30 seconds, compared to two minutes or more for Exchange Server 2007.

Another new feature called shadow redundancy will enable two copies of an e-mail message to be kept so that administrators do not need to run a RAID backup.

Some smaller companies and branch offices may run all of their Exchange 2010 roles on a single server with up to 16 processor cores. But most should run multiple servers, for safety reasons, he said.

"We would much rather see you scale out than scale up," Smith said.

Servers performing client access duties need at least eight CPU cores and 8GB of RAM in Exchange 2010. Servers can have up to 12 cores, but more may lead slower performance due to "processor cross-talk," he said.