Your personal Blackberry on a BIS is not on your corporate BES server. It wonxxx8217;t delete emails on your BB but will reflect the change from the BB. The BB is accessing your company email to do the delete. It is very unusual that a company allows internet access to its internal servers. You would need your own email on your companies BES server to control your own personal email.
Read how the BIS service works.
http://www.blackberry.com/btsc/micro...0%201046546322