Then have a look at these security hardening guides
from CIS (Center for Internet Security)
IS_Benchmark_Exchange2007_1.0.pdf - the Benchmark document contains detailed instructions for implementing the steps necessary to harden a Exchange Server 2007 installation.
Windows Server 2003 Domain Controllers (v1.2) - consensus settings for Legacy, Enterprise, and Specialized security levels for Windows Server 2003 Domain Controllers.
But I just love the first statement in the user agreements and it’s so true :-)
1. No network, system, device, hardware, software, or component can be made fully secure;
Have fun :-)
Tonino Bruno | ICT Consultant | Pro-Exchange Community