z Custom properties in Active Directory that an administrator has added (for example, the
Employee ID of each employee)
z Organization hierarchy information
z Group membership information
Article ID: 841273 - Last Review: March 4, 2009 - Revision: 8.0
Administering the offline address book in Outlook 2003 and Outlook 2007
Microsoft Office Outlook 2007 and Microsoft Office Outlook 2003 have many new features and
enhancements that are related to the offline address book. By default, Outlook uses a cached
mode configuration. Because cached mode generates an offline address book, understanding how
to configure the offline address book so that it works efficiently in your Microsoft Exchange
organization is important.
To make it easy for you to find the information you want, this article is organized in categories in a
Q1: What is cached mode?
A1: Cached mode is the new default configuration for Outlook. It provides an experience that is
similar to the offline configuration in earlier versions of Outlook. When you are running in cached
mode, your Exchange mailbox is synchronized to a local file (an .ost file), and the offline address
list from your Exchange computer is synchronized to a collection of files (.oab files) on your client
computer. Outlook directly accesses the .ost file and the .oab files on your hard disk instead of
communicating directly with your server or servers. Therefore, network communication between
Outlook and Exchange is significantly reduced.
Q2: Why does cached mode generate an offline address book?
A2: The offline address book contains a set of all the properties of a user (such as e-mail
addresses and names) that Outlook requires. With an offline address book, Outlook does not have
to connect to the global catalog to resolve names, nor does it have to open a person’s details
record. Instead, Outlook easily obtains this information from the local offline address book.
Q3: Does the offline address book fun