Microsoft Outlook acceleration provides improved performance for traffic between Microsoft Outlook clients and Microsoft Exchange Servers, increasing throughput with a variety of optimizations, including data prefetching and compression.
This feature is also called "MAPI acceleration," after the MAPI protocol used between Outlook and Exchange Server.
In networks where the Outlook data stream is unencrypted (the default before Outlook 2007), this feature requires no configuration.
In networks where the Outlook data is encrypted (the default with Outlook 2007 and later), acceleration can be obtained in one of two ways: by disabling encryption in the Outlook clients or by having the appliances join the Windows domain.
Encryption was disabled by default before Outlook 2007. Starting with Outlook 2007, encryption is enabled by default.