http://www.microsoft.com/downloads/details.aspx?FamilyID=371add31-d7a0-4c8b-8325-a6fced2d05e6&displaylang=en

 Along with a new version of the MAPI download:

http://www.microsoft.com/downloads/details.aspx?familyid=e17e7f31-079a-43a9-bff2-0a110307611e&displaylang=en

Once the new MAPI download has been installed you should no longer have to disable MAPI Encryption on the Client Access Server

Read more about it here:

http://msexchangeteam.com/archive/2009/12/09/453486.aspx