May i use JetStress in a production eviroment?
WHy not, You can use jetstress of Exchange 2007 and 2010. But Jetstress testing should be performed before you install Exchange on the server.
Install Jetstress
http://technet.microsoft.com/en-us/library/ff459260.aspx
Microsoft Exchange Server Jetstress
http://technet.microsoft.com/en-us/library/bb643093(EXCHG.80).aspx
Notes have been added to run jetstress on a production enviornment. Download below
http://gallery.technet.microsoft.com/Jetstress-Field-Guide-1602d64c