Disable encryption on the Exchange server

For 2007, 2010, and 2013 Exchange servers, Exinda recommends that encryption of the MAPI protocol should be disabled to maximize reductionmeasures the amount of redundant data that has been removed from the network, increasing capacity, as each user will encrypt files with a different key. You must disable encryption on all Microsoft Outlook clients as well as the Exchange server to maximize the benefit. See For more information refer to Turn off MAPI encryption in Microsoft Outlook.

NOTE

Encryption cannot be disabled on Exchange 2003 servers, but it will not enforce a policy requiring encrypted communications between Exchange and Outlook.