Hi Praveen,
As you know the WSA can inspect HTTP/HTTPS/FTP but email protocols are handle by C-Series.
Based on the apple link below the Exchange aplication will use port 993 to recieve emails and in order to send emails it needs ports 587, 465, or 25
http://support.apple.com/kb/ht1421
So this traffic shouldn't be getting to the WSA.
HTH
Luis Silva
"If you need PDI (Planning, Design, Implement) assistance feel free to reach"
http://www.cisco.com/web/partners/tools/pdihd.html
Luis Silva