Microsoft Exchange Server 2013 : Addressing Exchange - The Offline Address Book (part 3) - Creating and using customized OABs

Creating and using customized OABs

The foundation for the OAB is provided by a set of one or more address lists. The default OAB contains just one address list, the default GAL, so any object that is included in the GAL is also included in the default OAB. An address list is nothing more than a convenient way for Exchange to focus on a set of mail-enabled Active Directory objects by applying a filter to locate the objects. The filters are very similar to those used to create the membership of dynamic distribution groups. Each address list has a filter, and when Exchange generates an OAB, it applies the filter for each address list that is included in the OAB. Thus, when Exchange generates the default OAB, it applies the default GAL filter to find all the mail-enabled objects in the organization that are not marked to be hidden from address lists.

You can change the OAB that is provided to Outlook clients in two ways. First, you can use ABPs to assign customized versions of the GAL to usersSecond, you can create one or more OABs and assign these to specific users by assigning an OAB to a database so that every mailbox in that database uses that OAB, or you can do it by individual mailbox.

If your Exchange organization supports a common set of users that everyone needs to know, there is no need to replace the default OAB because it will serve the purpose of offline access to the directory well. Nevertheless, hosting companies that deliver Exchange services to other companies use address lists to provide a customized OAB for each company of the users that belong to one.

Before you get too far into creating a new OAB, remember that OABs are only useful to Outlook clients that work in cached Exchange mode. Clients that work online have access to the complete GAL unless they are constrained by ABPs. The discussion presented here focuses on the steps an Exchange administrator has to execute to create a customized OAB for specific mailboxes when she does not want to deploy ABPs for some reason.

Your first task is to create a suitable address list. You can create a new address list that contains all the mail-enabled objects for the location or create an address list for each object type (contacts, rooms, equipment, mailboxes, and groups) that are then combined in the OAB you eventually generate. Exchange maintains default address lists such as All Rooms or All Contacts to make it convenient to locate these objects for different purposes within the product. In this case, multiple address lists would probably overcomplicate matters, so to keep things simple, create a single address list.

When you create a new OAB, Exchange creates a directory to hold the files clients download to access the OAB under the \V15\ClientAccess\OAB root (Figure 3). Each OAB holds its files in a separate directory, naming the directory after the GUID for the OAB. By looking at Figure 3, you know that this organization supports two OABs. To see the GUIDs for the OABs so that you can associate the OABs with their directory, run the Get-OfflineAddressBook command that follows. You can see from the output how easy it is to locate the files for a particular OAB.

Figure 3. OAB directories on an Exchange 2013 server

Get-OfflineAddressBook | Format-Table Name, GUID –AutoSize

Name                                      Guid
----                                      ----
Default Offline Address Book              682524d0-c92b-400b-8e10-474a0f43cf03
Contoso Ireland OAB                       75027a4f-4d1a-4d8a-a662-003a4bd66d37

A particular OAB can be assigned to individual mailboxes or to all the mailboxes in a database. Use the Set-Mailbox cmdlet to assign an OAB to a mailbox. For example:

Set-Mailbox –Identity 'David Jones' –OfflineAddressBook 'Contoso Ireland OAB'

After a specific OAB has been assigned to a mailbox, anytime that the user attempts to download the OAB with Outlook, he’ll see that the OAB presented by Outlook (Figure 4) is based on a different GAL. Then again, he might not notice that such a subtle change has occurred!

Figure 4. Selecting an OAB to download with Outlook

You replace Set-Mailbox with Set-MailboxDatabase to make the assignment for a mailbox database:

Set-MailboxDatabase –Identity 'DB1' –OfflineAddressBook 'Contoso Ireland OAB'

Alternatively, you can select the database from EAC and access the Client Settings tab (Figure 5) to select the OAB there. If an OAB is not explicitly selected for a mailbox database, Exchange uses whatever OAB is the current default. To make a new OAB the default across the organization, you use a command like that shown here. Only one OAB can be marked as the default at one time.

Figure 5. Setting a new OAB for a mailbox database

Set-OfflineAddressBook –Identity 'Contoso Ireland OAB' –IsDefault $True

The steps presented here create and distribute a new OAB to users, but this won’t prevent them from accessing the default GAL when they work online with either Outlook or Outlook Web App.