The Microsoft Exchange Best Practices Analyzer will help you confirm that your server is configured correctly and flag any errors.
Microsoft Exchange Best Practices Analyzer - Exchange 2000 and 2003
This is the tool for Exchange 2000 and 2003. http://www.microsoft.com/en-us/download/details.aspx?id=22485
Microsoft Exchange Best Practices Analyzer - Exchange 2007 and 2010
For Exchange 2007 and 2010, the best practices analyzer is built in to the product. For more information on accessing them - click here for Exchange 2007 and here for Exchange 2010.