On the exchange server -
Open up Active directory users and computers right click on the username or contact and click properties in there pick Exchange Advanced tab and in there check the Hide from exchange address lists.
Some of the other problems I have found with using cahed mode is the following
1) From time to time the outlook client will go to offline mode and not send and recieve emails.
2) GAL not being an instant change.(缺省是一天更新一次)
3) HDD space use due to caching.
4) And once I even had outlook no longer opening giving errors due to a corrupted cached file.
see also
Administering the offline address book in Outlook 2003 and Outlook 2007