If you have the joy of administrating a Microsoft Exchange Mail Server and need a nifty tool for analyzing i can highly recommend the Microsoft Exchange Best Practices Analyzer
The analyzer will help you find sources of instability and performance problems and will assist you in configuring general policies for eMail usage.
Great tool and until today, never heard of it. Sometimes i just wish Microsoft would include tools like these directly into their products – or at least with the occasional service packs.