Administering the offline address book in Outlook

General information

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 function exactly like the global address list?

A3: The offline address book is a snapshot of the Active Directory directory service information that is available in the global address list. Therefore, some information is available in the global address list that is not available in the offline address book. The offline address book does not contain the following items that are available in the global address list:

• Custom properties in Active Directory that an administrator has added (for example, the Employee ID of each employee)
• Organization hierarchy information
• Group membership information

Outlook must be able to access the server to obtain this information. Therefore, if you are in cached mode and if you are working online (that is, your connection status indicates “Connected”), Outlook uses both the offline address book and the global address list to provide a complete listing of user information. If you are in cached mode and if your connection status shows either “Disconnected” or “Offline,” you can see only the information that is available in the offline address book.



Q4: What are the new offline address book features with Microsoft Exchange Server 2003?

A4: Exchange 2003 supports a Unicode offline address book. The Unicode version is also known as Version 3a. Exchange 2003 also supports earlier ANSI versions of the offline address book for Outlook clients with earlier versions. The ANSI version is also known as Version 2. Exchange 2003 computers also have a filtering mechanism in place that makes sure that only those certificates that are used by Outlook for public key infrastructure (PKI) will be present in the offline address book. This mechanism significantly reduces the size of the offline address book from servers that are running Exchange 2003 compared to the offline address book from servers that are running earlier versions of Exchange. The reduction applies to both the Unicode version and the ANSI version.

Downloading and updating

Q5: How frequently is the offline address book updated on the Outlook client?

A5: If left constantly running, Outlook in cached mode automatically updates the offline address book on the client every 24 hours. The 24-hour time period is measured from the time that the offline address book was last downloaded successfully. For example, if you complete an offline address book download at 09:00 today, Outlook will start the offline address book download the next day at approximately 09:00. Therefore, different people will receive updates at different, random times.

Note The default setting on Exchange Server 2010 and earlier versions is to generate an offline address book differential file every morning at 05:00. For a change that is made in Active Directory to reach the client computer, the following events must occur:

• The change must be picked up by the Exchange computer that generates the offline address book files. This can take several hours. At worst, it can take 24 hours. This variable will be referred to as "x."
• The Outlook clients must download the offline address book updates every 24 hours. This update can take several hours. At worst, it can take 24 hours. This variable will be referred to as "y."

The update reaches the client machines x+y hours later. It would be rare for a client to ever experience a 48-hour delay or more unless there were some Active Directory or public folder replication issues.

Note For Exchange Server 2013 and later versions, the default schedule is to process the OAB every 8 hours over a period of 1 hour. OAB generation can run at different times based on resource availability.



Q6: How can you tell when Outlook will try its next offline address book download?

A6: Unless you notice the last time that Outlook downloaded the offline address book, you may not know when Outlook is scheduled to try the next offline address book download. No indicator in the Outlook user interface advises you of the offline address book download schedule. Therefore, to manually force a download of the latest offline address book (assuming one is available on the Exchange computer), use one of the following methods:

• Manually download the address book by following the steps appropriate for your versions of Outlook.
  
  
  • Outlook 2010 and later versions:
    On the Send/Receive tab in the Ribbon, click Send/Receive Groups, and then click Download Address Book. Click OK.
    
  • Outlook 2007 and earlier versions:
    On the Tools menu, point to Send/Receive, and then click Download Address Book. Click OK.
  
  Note Outlook compares the sequence ID of its last download with the Sequence ID of the Full/Differential OAB file on the Exchange server. If Outlook determines that either sequence ID is high as compared to the sequence ID that was downloaded, Outlook triggers the download.

Q7: How frequently are the offline address book files generated on the Exchange computer?

A7: By default, Exchange Server 2010 and earlier versions generate the offline address book files every morning at 05:00. For Exchange Server 2013 and later versions, the default schedule is to process the OAB every 8 hours over a period of 1 hour. OAB generation can run at different times based on resource availability.



Q8: How is the offline address book updated on the server and on the client?

A8: Each day, the Exchange computer generates a full offline address book and a differential file from the previous day. The Exchange computer stores the differential file and the full file for the current day and stores only the differential files for the previous days.

The following table outlines the process that Exchange and Outlook use to determine which offline address book files to download to the client.



Q9: What are typical offline address book sizes?

A9: Offline address book sizes can vary from 3 megabytes (MB) to 700 MB (uncompressed). The following factors can affect the size of the offline address book:

• The usage of certificates in a company. The more PKI certificates, the larger the offline address book. PKI certificates range from 1 kilobyte (KB) to 3 KB. They are the single largest contributor to the offline address book size.
• The number of users in Active Directory.
• The number of distribution groups in Active Directory.
• The information that a company adds to Active Directory for each user and each distribution group. For example, some organizations populate the address properties on each user; others do not.

Q10: Can I update the offline address book files on the Exchange computer more frequently?

A10: We do not recommend that you update more frequently as this may affect client and server performance. Generating the offline address book files on the Exchange computer on a more frequent basis may cause performance problems on the server. You can see the performance impact in the following aspects:

• The server has to generate the offline address book more frequently. It might take hours to complete, depending on the size of Active Directory.
• For each update, Outlook must make a copy of the offline address book in the local computer and apply the incremental changes that are fetched from the server. If the offline address book on the local computer is 150 MB, Outlook would have to create a copy of that much data with each update.
• Outlook has a "throttling" mechanism that slows down the offline address book update when user activity is detected. Depending on the size of the offline address book, the update can take anywhere from one hour to eight hours if there is continuous user activity.

If you want to increase the frequency of your updates, make sure your offline address book is reasonably small. A good size is in the range of 1 MB to 25 MB, uncompressed.

To customize the generation of these files on the server, follow these steps.

Exchange Server 2003 and Exchange Sever 2007:

1. In Exchange System Manager (ESM), expand the Recipients container.
2. Click Offline Address Lists.
3. Right-click the offline address list that you specified for your mailbox store, and then click Properties.
4. Click Customize.
5. Customize the times that you want the offline address book files to be generated on your server.

Exchange Server 2010:

1. In Exchange Management Console (EMC), expand the Organization Configuration, container and then click Mailbox.
2. In the result pane, click the Offline Address Book tab, and then select the offline address book that you want to configure.
3. In the action pane, click Properties.

If you have increased the generation frequency of the offline address book files on your Exchange computer, you can also increase the frequency of the client offline address book downloads. To do this:

1. On the Tools menu, point to Send/Receive, point to Send/Receive Settings, and then click Define Send/Receive Groups.
2. Click New.
3. Type a name for the custom group.
4. Click your Exchange account, and then click to select the Include the selected account in this group check box.
5. Under Select the options you want for the selected account group, make sure that the only check box that is selected is Download offline address book, and then click OK.
6. In the Send/Receive Groups dialog box, click your new group.
7. Under Setting for group Group_name, click to select only the Schedule an automatic send/receive every check box, and then enter the number of minutes.
8. Under When Outlook is offline, click to clear the check boxes.
9. Click Close.

With the custom send/receive group, Outlook will request an offline address book download from the server based on the number of minutes that you specified for the send/receive setting.

Note Send/receive groups cannot be deployed. No tool or other mechanism is available to deploy send/receive group settings.



Q11: Can I programmatically download an offline address book through the Outlook object model?

A11: No. Offline address book downloads are not exposed through the Outlook object model.



Q12: I added a new user to Active Directory, but the user does not show up in Outlook.

A12: The offline address book is not up to date. Two events must occur before the changes show up in Outlook:

• The server must generate the offline address book and include the changes in the differential files.
• The Outlook client must download the changes from the server.

If you are sure that the first event has occurred, you can perform a manual download of the offline address book. To do this, follow these steps:

1. On the Tools menu, point to Send/Receive, and then click Download Address Book.
2. In the Offline Address Book dialog box, make sure that the Download changes since last Send/Receive check box is checked.
3. Click OK.

If you make frequent changes to the offline address book, you may want to modify the way that Outlook computers on your network access the Address Book. You can disable the downloading of the offline address book and force the Outlook computers to use the online Global Address List when they use Cached Exchange Mode.

For more information about how to do this, click the following article number to view the article in the Microsoft Knowledge Base:

921927 How to prevent users from downloading the Offline Address Book without disabling Cached Exchange Mode

As per this article, if offline address book (.oab) files were previously downloaded and were associated with a MAPI profile for Outlook, this setting will not have the correct effect. To use this setting, you must set the registry value, remove any .oab files from the local computer, and then synchronize.



Q13: What is the effect of offline address book downloads on the network? Will offline address book downloads flood the network?

A13: When a cached mode profile is started for the first time, Outlook downloads the full offline address book from the server. This can affect the network, especially if multiple clients are starting up at the same time.

Other cases when Outlook clients require full offline address book downloads are described in question 14. Differential downloads are not expected to cause a huge network impact if all the clients update the differential files on a daily basis.

Outlook has the following safeguards that help protect the network from excessive offline address book downloads:

• In the default configuration, Outlook will only try one full offline address book download in a 13-hour period. An attempt is counted when Outlook receives a response from the server and can at least start the offline address book download.
• In the default configuration, Outlook does not limit the number of attempts for differential updates. If a differential update fails, Outlook will retry the update after waiting one hour.

Also, Outlook will not perform any full or incremental offline address book downloads if the client is running in header-only mode. In the default configuration, when Outlook detects a “slow” connection, such as a 56-KB link, it will automatically switch to header-only mode. To manually switch to header-only mode, point to Exchange Cached Mode on the File menu, and then click Download Headers.

Note The header-only mode configuration will only work with Exchange 2003. Microsoft Exchange 2000 Server and Microsoft Exchange Server version 5.5 do not support this mode.

Q14: Under what conditions will Outlook perform a full offline address book download?

A14: Outlook in cached mode will perform full offline address book download when the following conditions are true:

• There is no offline address book on the client computer. This condition may occur if Outlook has not performed an initial complete synchronization.
• The total size of the differential files is greater than one-eighth the size of the full offline address book. In this case, Outlook downloads the full offline address book for better performance. This condition may occur if there are lots of Active Directory objects that have a change to an attribute that is in the offline address book. For example, phone numbers are updated with a new area code, departments are added to all users in Active Directory, and new address types are added.
  
  To modify the one-eighth rule, follow these steps.
  
  Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
  322756 How to back up and restore the registry in Windows
  
  
  
  1. On the Outlook client computer, click Start, click Run, type regedit, and then click OK.
  2. Locate and then click the following registry subkey:
     HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Exchange\Exchange Provider
  3. If the OAB Dif Divisor entry is not present in the right pane, create it. To do this:
     
     
     1. In the left pane, right-click the Exchange Provider subkey, point to New, and then click DWORD Value.
     2. Type OAB Dif Divisor, and then press Enter.
  4. Double-click OAB Dif Divisor.
  5. In the Edit DWORD Value dialog box, type 4 in the Value box, and then click OK.
     
     This setting example (4) permits Outlook to download differential offline address book files that are up to one-fourth the size of the full offline address book.
     
     Note If the OAB Dif Divisor registry value is set to 0 (zero), Outlook will use 16 so that it does not divide by 0.
  6. Exit Registry Editor.

• The parent distinguished name table changes. When this behavior occurs, all Outlook clients will also try to perform a full download. The change may have occurred if a new PDN is created or if a PDN is removed.
  
  A parent distinguished name is the part of a distinguished name (also known as DN) in an earlier Exchange format, not including the final relative distinguished name (also known as RDN). For example, /o=org/ou=site/cn=Recipients/cn=bob has a parent distinguished name of o=org/ou=site/cn=Recipients.
  
  The parent distinguished name table is the set of all parent distinguished names that are found in Active Directory. They come from the legacyExchangeDN attribute and from the proxyAddresses attribute, and they start with the following prefix:
  x500:
  X500 addresses are only included if they start with /o=orgname, where orgname is the actual name of the local Exchange organization. This means that x500 addresses for users who were migrated from another organization will not be included.
• There is a differential file missing on the server. Outlook cannot update to the current version without it. This behavior may occur if one of the following conditions is true:
  
  
  • You did not start Outlook (to log on to your Exchange mailbox) for more than 30 days. The server policy permits only 30 days of differential files.
  • There was an error on the server, and it did not generate the differential file for a day.
  • The server was reset, or it crashed before it could post the differential files but after it was able to post the full offline address book files on the public folder.
• The version on the server and the version on the client do not match. There is a more recent version of the offline address book present on the server. For example, Version 3a (Unicode offline address book) is now available, and you previously downloaded a Version 2 offline address book.
• Applying changes to the offline address book failed. For example, differential files are corrupted on the server. Corruption may occur if the server goes down during differential file generation.
• A change to the legacyDN table occurred. For example, a new legacyDN table is added, or an existing legacyDN table is deleted from Active Directory.
• One or more offline address book files were not present on the client computer. For example, a user accidentally deletes one of the .oab files on the user's computer.
• A previous full download failed, and Outlook has to start from the beginning.
• You manually download the offline address book.

Note Outlook will not perform a full download if there is a disk-space problem on the client computer. This restriction helps safeguard the network against excessive downloads.



Q15: Is there any compression of the data during an offline address book download?

A15: To save bandwidth, the offline address book is compressed to less than one-third of its full size during the download. You can verify the size of your organization’s offline address book by going to its storage location in the Exchange system public folder. You can see the full offline address book files by using Outlook Web Access with a URL that is similar to the following:For estimation purposes, the full offline address book size is approximately 1 MB per 1,000 users. If there are user certificates in the offline address book, this will add approximately 1 KB per certificate.



Q16: Outlook shows the "Updating Address Book" status for a long time. Why?

A16: Outlook has a throttling feature that slows the address book update when you are working in Outlook. This can cause the “Updating Address Book” status appearing for a long time. Outlook is helping you complete other activities and does not allow the address book update to interfere.



Q17: My computer slows down when Outlook shows the "Updating Address Book" status. Why?

A17: In computers with slow hard disk drives, such as some earlier portable computers, the process of updating the address book can slow down the computer if the hard disk is fragmented. To improve offline address book download performance, try defragmenting your hard disk. For more information, view the following article in the Microsoft Knowledge Base:

Ways to improve your computer's performance

Q18: Do send/receive settings affect automatic 24-hour offline address book downloads?

A18: The Download offline address book check box in the Send/Receive Settings - "Group_name" dialog box does not affect the 24-hour download process. In fact, Outlook cached mode will continue to download the offline address book every 24 hours regardless of whether the option is enabled.

Note To locate this option, follow these steps for your version of Outlook:


Outlook 2010 or later versions:

1. On the Send/Receive tab in the Ribbon, click Send/Receive Groups, and then click Define Send/Receive Groups.
2. Click your account group, and then click Edit.

Outlook 2007 or earlier versions:

1. On the Tools menu, point to Send/Receive, point to Send/Receive Settings, and then click Define Send/Receive Groups.
2. Click your account group, and then click Edit.

When you click to select the Download offline address book check box and then click Address Book Settings, the Offline Address Book dialog box appears. In this dialog box, you can specify either No Details or Full Details. These settings affect the offline address book download. For example, if you select No Details, a no-details version will be automatically downloaded to your computer during an offline address book download.



Q19: How can I determine whether my client is performing a full offline address book download?

A19: To have Outlook display a dialog box that prompts you before the offline address book download starts, follow these steps.

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

322756 How to back up and restore the registry in Windows

1. On the Outlook client computer, click Start, click Run, type regedit, and then click OK.
2. Locate and then click the following registry subkey:
   HKEY_CURRENT_USER\Software\Microsoft\Exchange\Exchange Provider
   
3. If the Allow Full OAB Prompt entry is not present in Name column in the right pane, create it. To do this:
   
   
   1. On the Edit menu, point to New, and then click DWORD Value.
   2. Type Allow Full OAB Prompt, and then press Enter.
4. Right-click Allow Full OAB Prompt, and then click Modify.
5. Type 1, and then click OK.
   
   Set this value to 1 to display the prompt. Set it to 0 to not display the prompt.

When Outlook starts the offline address book download, a dialog box prompts you to select whether you want to perform a full download. If you click No, Outlook will prompt you again after one hour.



Q20: Are ANSI offline address book files deleted when Outlook downloads a Unicode offline address book?

A20: When an Outlook profile switches from ANSI mode to Unicode mode, Outlook will delete the old ANSI offline address book files. However, Outlook only deletes the offline address book files that belong to the current profile. If you create a new Unicode profile, you may still see some old ANSI offline address book files if these files are associated with another Outlook profile.

Resolving names

Q21: How can I indicate that I want exact alias matching with the offline address book?

A21: When you use Outlook in cached mode, a registry setting controls how names are matched to the offline address book. By default, name fragments are matched to all naming fields, not just to the e-mail alias. For example, the following table contains examples of how names are resolved in Outlook in cached mode.



If you type bobb in an Address field, Outlook resolves "bobb" to both entries in cached mode.

You can indicate that you want an exact match for an e-mail alias by typing an equal sign before the e-mail alias text. For example, if you type =bobb, Outlook resolves "bobb" to Bob Brewer.

If you are using Outlook in cached mode, you can turn on exact e-mail alias matching without having to use the equal sign. To use this function, follow these steps.

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

322756 How to back up and restore the registry in Windows

1. Click Start, click Run, type regedit, and then click OK.
2. Locate and then click the following registry subkey:
   HKEY_LOCAL_MACHINE\Software\Microsoft\Exchange\Exchange Provider
3. On the Edit menu, point to New, and then click DWORD Value.
4. Type OAB Exact Alias Match, and then press Enter.
5. Right-click OAB Exact Alias Match, and then click Modify.
6. Type 1, and then click OK.
   
   Setting this value to 1 enables exact matching.

Q22: The My Name property in Active Directory is set to "Lastname, Firstname," and I cannot resolve Firstname. Why?

A22: The offline address book supports name resolution indexes against the following properties only:

• Lastname
• DisplayName
• Alias
• OfficeLocation
• Primary SMTP Address
• Primary X500 Address

Conversely, Active Directory is configurable. Your administrator can set the server to resolve names against any set of properties. The limited indexes in the offline address book work well for organizations that have the name set in Active Directory as “Firstname Lastname.” The following sample user information illustrates why name resolution works well in this configuration:

• Lastname: Santos
• DisplayName: Marcelo Santos
• Alias: MSantos
• OfficeLocation: 18/2231
• Primary SMTP address: MSantos@exchange.contoso.com
• Primary X500 address: /o=Contoso/ou=APPS/cn=recipients/cn=msantos

With this configuration, you can find this user by typing “Marcelo” or “Santos” or “Marcelo Santos”.

If Active Directory had the display name set to "Lastname, Firstname," the following values would be indexed for the properties in the sample user information:

• Santos
• Santos, Marcelo
• MSantos
• 18/2231
• msantos@exchange.contoso.com
• /o=Contoso/ou=APPS/cn=recipients/cn=msantos

In this configuration, you cannot find this user if you type "Marcelo." There is no property in the second list that begins with “Marcelo.”

If Active Directory is set to "Lastname, Firstname" in an organization and if there is an absolute requirement to provide Firstname resolution, you must install Microsoft Office 2003 Service Pack 2 (SP2). This problem does not occur with SP2 because the offline address book for SP2 downloads the PR_GIVEN_NAME attribute. If installing SP2 is not an option, you must perform additional steps for non-SP2 clients. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

831124 How to force Outlook 2007 or Outlook 2003 to resolve proxy addresses and custom properties in Cached Exchange Mode

Article 831124 recommends that you disable the name resolution that is provided by the offline address book. This can reduce the effectiveness of cached mode because Outlook must have the global catalog server to resolve names.



Q23: I cannot resolve proxy addresses now. Why?

A23: The offline address book supports resolving names against the DisplayName, Lastname, OfficeLocation, Alias, and Email address fields. If these fields do not meet your requirements, you can force Outlook to resolve proxy addresses.For more information, click the following article number to view the article in the Microsoft Knowledge Base:

831124 How to force Outlook 2007 or Outlook 2003 to resolve proxy addresses and custom properties in Cached Exchange Mode

NOTE: There are some limitations to how proxy addresses are resolved even after implementing the information in article 831124. Please see the details in article 831124 for additional information.

Q24: Can I add a custom property to the offline address book?

A24: No. You cannot add custom properties directly to the offline address book. Any custom properties that are added to the General tab of the "User_name" Properties dialog box must be retrieved from the global catalog server when Outlook is online. This can cause remote procedure call (RPC) traffic to the server and can cause delays if these properties are published to the General tab. We recommend that you add these custom properties to alternative tabs. For example, add the custom information in the Notes field on the Telephones tab of the "User_name" Properties dialog box in Active Directory Users and Computers. This information will appear in the Notes box on the Phone/Notes tab in the "User_name" Properties dialog box in the offline address book.

For more information about resolving custom properties when using Outlook, click the following article number to view the article in the Microsoft Knowledge Base:

831124 How to force Outlook 2007 or Outlook 2003 to resolve proxy addresses and custom properties in Cached Exchange Mode

Q25: Can I download more than one offline address book? Can I use two cached profiles with their own offline address books?

A25: No. Outlook supports only one offline address book per user account on a computer. If you have multiple profiles, only one profile can download the offline address book. If you have to use two cached mode profiles, make sure that one of the profiles does not download the offline address book.

For more information about how to disable the Outlook Address Book download for a cached mode profile, click the following article number to view the article in the Microsoft Knowledge Base:

823580 How to configure how the Offline Address Book is downloaded when you use Outlook in Cached Exchange Mode

Q26: How can I determine whether Outlook is using the offline address book on the local computer?

A26: To determine whether Outlook is using a downloaded offline address book or the global address list, follow these steps:

1. Open a new message, and then click To:.
2. In the Show Names from the list, right-click Global Address List, and then click Properties.
   
   If you see a local file path, such as C:\Users\..., Outlook is using the downloaded offline address book. If you see a server name, such as Win2003GC, Outlook is going online for this information, and you have not yet completed a full download of the offline address book.

Q27: Can offline address books be shared on one computer among multiple profiles?

A27: No. The information that relates to an offline address book is stored per profile. Offline address books cannot be shared among multiple profiles.



Q28: How can I download a Unicode offline address book?

A28: By default, if you are connected to a server that is running Exchange 2003 or later, the offline address book that is downloaded is a Unicode offline address book. If you are connected to a server that is running either Exchange 2000 or Exchange 5.5, you will always download an ANSI offline address book.

The basic rules are:

• If Outlook is running in Unicode mode, Outlook tries to download a Unicode offline address book. If a Unicode offline address book is not available, Outlook downloads an ANSI offline address book.
• If Outlook is running in ANSI mode, Outlook will always download an ANSI offline address book.

Note If your computer is running Exchange 2003 or later, your profile must also be set to Unicode mode to download a Unicode offline address book. To check the mode for your profile, follow these steps for your version of Outlook:

Outlook 2010 and later versions:

1. On the File tab, click Account Settings, and then click Account Settings.
2. Click your Exchange account, and then click Change.
3. Click More Settings.
4. Click the Advanced tab.
5. Note the description under Mailbox Mode.
6. If you are running in non-Unicode mode and you are using an Exchange 2003 or later versions, try creating a new Outlook profile to change over to Unicode mode.

Outlook 2007 and earlier versions:

1. On the Tools menu, click Account Settings.
2. Click your Exchange account, and then click Change.
3. In the Change E-mail Accounts dialog box, click More Settings.
4. Click the Advanced tab.
5. Note the description under Mailbox Mode.
6. If you are running in non-Unicode mode and you are using an Exchange 2003 or later versions, try creating a new Outlook profile to change over to Unicode mode.

Q29: Must I have a full-details offline address book for cached mode, or can I work with a no-details offline address book instead?

A29: Outlook cached mode relies on the information present in the full-details offline address book to provide a smooth cached mode experience. A no-details offline address book does not have all the properties that Outlook requires to function without the server access. The lack of properties might make Outlook unresponsive at certain times.



Q30: What containers are present in the offline address book?

A30: The offline address book supports only a single “container." The following example illustrates how this impacts Outlook:

1. Open a new e-mail message in a cached mode profile.
2. Click To:.
   
   The Show names from the list displays the global address list as the default container.
3. Right-click Global Address List, and then click Properties.
   
   Under The current server is, the local path of the offline address book files is displayed. This indicates that the global address list is being used as the container for the offline address book. In this configuration, whenever you select a name from the global address list, you will not see any network traffic between your client and the server.
4. In the Global Address List Properties dialog box, click OK.
5. Click the Show names from the list.
6. Note the additional containers under All Address Lists. None of these containers are in the offline address book.
7. Under All Address Lists, click a container. For example, click All Contacts.
   
   If you click a name in the All Contacts container, Outlook will download the information from the server and not from the local offline address book.

Q31: Where are the offline address book files located?

A31: The offline address book files are located in the following locations, depending on the version of Windows that you are running.

Windows 10, Windows 8, Windows 7 or Windows Vista:
%userprofile%\AppData\Local\Microsoft\Outlook

Windows XP or earlier versions:
%userprofile%\Local Settings\Application Data\Microsoft\Outlook

The folder contains six files for a full-details offline address book or five files for a no-details offline address book. The file names identify whether the offline address book is in Unicode format or in ANSI format. The following table lists the file names that are included.



Q32: I do not have space on drive C. Can I move the offline address book to another drive?

A32: Yes. To move the offline address book, follow these steps.

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

322756 How to back up and restore the registry in Windows

1. Click Start, click Run, type regedit, and then click OK.
2. Locate and then click the following registry subkey appropriate for your version of Outlook:
   
   
   • Outlook 2013 and later versions:
     HKEY_CURRENT_USER\Software\Microsoft\Office\x.0\Outlook\Profiles\Profile_name\13dbb0c8aa05101a9bb000aa002fc45a
     
     NoteThe x.0 placeholder represents your version of Office (16.0 = Office 2016, 15.0 = Office 2013).
     
   • Outlook 2010 and earlier versions:
     HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows Messaging Subsystem\Profiles\Profile_name\13dbb0c8aa05101a9bb000aa002fc45a
   
   
3. On the Edit menu, point to New, and then click String Value.
4. Type 001e660e, and then press Enter.
5. Right-click 001e660e, and then click Modify.
6. In the Value data box, type the path of the folder where you want to store the offline address book files, and then click OK.
7. Exit Registry Editor.

For more information about cached mode and the offline address book, go to the following Microsoft websites: