JSI Tip 9567. Exchange Server 2003 Security Hardening Guide.

Microsoft Download Center page, Exchange Server 2003 Security Hardening Guide, contains the following overview:

Read the entire Exchange Server 2003 Security Hardening Guide online or download the Exchange Server 2003 Security Hardening Guide.This guide is designed to provide you with essential information about how to harden your Exchange Server 2003 environment. In addition to practical, hands-on configuration recommendations, this guide includes strategies for combating spam, viruses, and other external threats to your Exchange 2003 messaging system. Important: Since the previous version of this guide was released, the following new topics have been added and are available only online:
•Running Exchange Server 2003 Clusters in a Security-Hardened Environment
•How to Run Exchange Server 2003 Clusters in a Security-Hardened Environment