Book excerpt: Computer viruses and spam messages cost businesses and consumers billions of dollars every year. This book delivers the critical information that administrators, security architects, and messaging designers who work with Microsoft Exchange need to know to combat email viruses and spam. Written with assistance from the Microsoft Exchange team, it delivers critical information organizations of all sizes should know and practice. The book includes information not found in books about Exchange administration or Microsoft Windows. security and covers client-server, server-Internet, and server-client security.