Exchange Server Cookbook

Chapter 8. Client Connectivity

Introduction

Controlling how users connect to Exchange is a necessary part of administering Exchange servers. The recipes in Chapter 7 describe how to control SMTP connections, both originating from and terminating at the Exchange server. In this chapter, we’re going to consider how users connect to your servers with MAPI, WebDAV, POP, IMAP, NNTP, and Outlook Web Access. There are significant differences between how Exchange handles client interactions between these protocols, most of which stem from the protocol implementation. Several of the recipes within this chapter use registry keys in the solution—you should note that Group Policies may also be used to make these registry changes.

MAPI Clients

The venerable Messaging Application Protocol Interface (MAPI) has been around a long time, and reports of its death have been greatly exaggerated. As the primary protocol used by Outlook since its inception, MAPI is well entrenched in Exchange deployments. MAPI traffic is actually a series of remote procedure calls (RPCs) that pass between the client and the server; the contents of these RPCs aren’t publicly documented by Microsoft, and they have changed the ordering and contents of the RPC payloads in several successive versions of Outlook to improve efficiency and security. MAPI connectivity can be established directly between the client and the server or through the RPC-over-HTTP proxy feature added to Windows Server 2003, Exchange Server 2003, and ...