A. Outlook usually removes deleted data from the PST and OST when you close the application. To ensure that Outlook overwrites all deleted data when you close your mailbox, perform the following steps:

  1. Start a registry editor (e.g., regedit.exe).
  2. Navigate to the HKEY_CURRENT_USER\Software\Microsoft\Office\9.0\Outlook\PST subkey for Outlook 2000 or to the HKEY_CURRENT_USER\Software\Microsoft\Office\10.0\Outlook\PST subkey for Outlook 2002 (you might need to create the PST subkey if it doesn't exist).
  3. From the Edit menu, select New, DWORD Value.
  4. Enter a name of PSTNullFreeOnClose, then press Enter.
  5. Double-click the new entry, set the value to 1 (0 is the default setting) to instruct Outlook to remove the deleted data every time you close the application, then click OK.
  6. Close the registry editor.