If you don’t see the Security tab on your Exchange organization’s Properties tab, obviously you won’t be able to modify the security.
Here’s how you can enable the Security tab by modifying the registry.
1. Start the registry editor (regedit.exe).
2. Locate the following subkey: HKEY_CURRENT_USER\Software\Microsoft\Exchange\EXAdmin.
3. From the Edit menu, select New, and then select DWORD value.
4. Type ShowSecurityPage and press Enter.
5. Double-click the entry you just created and set the value to 1.
Close the registry editor. You should now have the Security tab in the Properties of your Exchange organization.
