The situation is below. I received this error when I tried to change proxyaddress. http://networkadminkb.com/KB/a160/how-to-fix-error-id-c10308a2-while-using-active-directory.aspx http://support.microsoft.com/kb/905809/en-us In Method 2 above : Add Read and Write permissions to the user account I found Right-click the Microsoft Exchange System Attendant service, and then click Properties. Microsoft Exchange System Attendant service does not exist in group policy. Why the service does not exist ?

Hello, can you provide a little more information, like: Which server are you running? Exchange version? What roles are installed on the specified server and which are on remote servers?

We use Win2003R2 DC and Exchange2003. We use RDP to Win2003 DC to change proxyaddresses value. We have full control security right on users by operations account and uses operation account to change proxyaddresses value but, I can not do it.

Hello, Please try changing the value via ADSIEDIT and see if there are any errors. Thanks, Simon

Thank you. I tried to edit by adsiedit but user is too many to display. So I tried to make query but, I can not browse Root of Search and can not start search.

Thank you very much. I could change proxyaddresses value from adsiedit by operation account. Why that ?