One of the primary strengths of Microsoft ISA Server is the ability to securely make Microsoft Exchange servers available to external clients. The procedures in this chapter assume that you already have Microsoft Exchange Server 2003 installed behind Microsoft ISA Server 2004 (Standard Edition or Enterprise Edition), and are using a single-domain environment.
For more detailed information about any of the steps listed here, as well as some scenarios we do not discuss, see the "ISA Server 2004/ Exchange Server Deployment Kit." This guide provides more than 700 pages of rich details for taking you through the process of configuring most Exchange Server/ISA Server scenarios step by step. You can download the guide from the Exchange Deployment Kit link at http://www.microsoft.com/isaserver/techinfo/guidance/2004/configuration.mspx.
We provide information on how to access Exchange through ISA Server in four ways:
Web-based access using Microsoft Outlook Web Access, using forms-based authentication
Message application programming interface (MAPI) client access, which allows one to take full advantage of all Microsoft Outlook features, including calendars and new mail notification
Secure connectivity for Outlook clients using Remote Procedure Call (RPC) over Secure HTTP (HTTPS)
Mail-only access using Post Office Protocol 3 (POP3) or Internet Message Access Protocol 4 (IMAP4) clients