Offline Address Book generation is set to update continuously

[This topic is intended to address a specific issue called out by the Exchange Server Analyzer Tool. You should apply it only to systems that have had the Exchange Server Analyzer Tool run against them and are experiencing that specific issue. The Exchange Server Analyzer Tool, available as a free download, remotely collects configuration data from each server in the topology and automatically analyzes the data. The resulting report details important configuration issues, potential problems, and nondefault product settings. By following these recommendations, you can achieve better performance, scalability, reliability, and uptime. For more information about the tool or to download the latest versions, see "Microsoft Exchange Analyzers" at]  

Topic Last Modified: 2006-12-04

The Microsoft® Exchange Server Analyzer Tool queries the Active Directory® directory service to determine whether the value for the offLineABSchedule attribute in the msExchOAB class has been configured for offline address book generation. The offLineABSchedule attribute determines the schedule for the offline address list. If the Exchange Server Analyzer finds that the offline address book generation schedule for the offline address list has been set to update continuously, the Exchange Server Analyzer displays an error.

An offline address book is a container that stores a collection of offline address lists. Administrators configure available offline address books. Microsoft Office Outlook® 2003 and Outlook 2007 users can choose which offline address lists they want to download. MAPI clients, such as Outlook 2003 and Outlook 2007, can download offline address lists. Therefore, users can compose e-mail messages even when they are disconnected from their Exchange server.

You can schedule when offline address lists are updated. However, make sure that you configure an update schedule that allows enough time for generation of the offline address list to complete before the next update starts. For example, there must be at least four hours between each update interval if the following conditions exist:

  • You specify three updates in a 24-hour period.

  • It takes four hours to update the offline address lists.

Frequent updating is generally not recommended because frequent updating may affect client and server performance in the following ways:

  • 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 on 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 must 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. When there is continuous user activity, the size of the offline address book affects the time that is required for updates. This time period can vary from one hour to eight hours.

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

To schedule a time for updating offline address lists in Exchange 2000 Server and Exchange Server 2003

  1. In System Manager, double-click Recipients, and then click Offline Address Lists.

  2. In the details pane, double-click the offline address list for which you want to set an update schedule.

    1. To choose a preconfigured update interval, in the General tab, select one of the intervals provided from the Update interval drop-down list.


      If you select Never run from the drop-down list, the offline address list will not be updated.

    2. To set a specific update schedule, click Customize. In the Schedule dialog box, set the update schedule on the day and time grid displayed, and then click OK.

To correct this warning for Exchange Server 2007

  1. Open the Exchange Management Console.

  2. Expand Microsoft Exchange, expand Organization Configuration, and then select Mailbox.

  3. In the results pane, click the Offline Address Book tab.

  4. On the Offline Address Book tab, select "Default Offline Address Book". In the action pane, click Properties.

  5. On the General tab, select the run time from the Update Schedule drop-down list, or click Customize to set a custom schedule.

  6. Click OK to save the changes.

To use the Exchange Management Shell to set Offline Address Book generation schedule

  • Run the following command:

    Set-OfflineAddressBook -Identity <OAB Name> -Schedule <Schedule>

    Where: <OAB> is the distinguished name (DN), Domain\Account name, or GUID of the OAB and <Schedule> specifies the scheduled times to start OAB generation and the format is StartDay.Hour:Minute [AM/PM]. You can use the following values for the days:

    • Full name of the day

    • Abbreviated name of the day

    • Integer from 0 to 6, where 0 = Sunday

    If you prefer to use a 24-hour clock, omit AM/PM.

    For example, to set the Default Offline Address Book generation schedule to daily between 1AM and 3AM, you would enter:

Set-OfflineAddressBook -Identity "\Default Offline Address Book" -Schedule 0.01:00-0.03:00,1.01:00-1.03:00,2.01:00-2.03:00,3.01:00-3.03:00,4.01:00-4.03:00,5.01:00-5.03:00,6.01:00-6.03:00

For more information, see the Offline Address Book Best Practices Guide (

For more information about working with offline address books in Exchange Server 2003, see "Configuring Exchange Server 2003 Offline Address Books" in Working with the Exchange Server 2003 Store (

For more information about working with offline address books in Exchange Server 2007, see "Organization Configuration > Mailbox > Offline Address Books" (