Auditing mailbox access on Exchange 2000 not working

[Modeverything]

I need to audit access to user's mailboxes in my Exchange 2000 organization. I understand that this is done through group policy auditing policies, but I have tried many different settings here.

Currently, some auditing is taking place. The exchange server seems to log some account logons indicating mailbox access, but it's logging probably only 1% of them. The global catalog server is also logging some events, but also not many, and it doesn't specify whether or not they are associated with mailbox access or any object in Exchange.

These auditing policies are configured domain wide and I have verfied they are applying to the Exchange server.

I currently have:
Audit Account Logon Events - Success and Failure
Audit Account Management - Success
Audit Directory Service Access - Success and Failure
Audit Logon Events - Success and Failure
Audit Object Access - Success and Failure
Audit Policy Change - Success and Failure
Audit Privilege Use - Failure
Audit Process Tracking - Failure
Audit System Events - Success and Failure



Thanks for any help anyone can provide.