Almost a year after Exchange 2013 went RTM, which was (IMO) just a marketing move to be part of the "Office wave" since it didn't become useful until earlier this year, Microsoft has released the Exchange 2013 Load Generator. I know that most folks won't care about this, but many of the vendors that you end up listening to for sizing guidance use these tools to be able to provide accurate guidance. Until now, only the Jetstress tool was made available and that only provides you with storage testing.
The LoadGen tool provides end-to-end testing of the entire Exchange stack (minus the UM pieces) and helps us to understand just how accurate the sizing guidance provided by Microsoft and the calculator really are. Download Exchange Load Generator 2013 at the link below:
http://www.microsoft.com/en-us/download/details.aspx?id=40726
-enjoy
