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Important Because of the complexity of the following instructions, do not try to complete the following instructions unless you are very familiar with the technical topics that are described or have administrative permissions.


This article describes how to troubleshoot problems with missing and duplicate appointments when you use Microsoft Outlook and Microsoft Exchange Server. It contains links to articles that describe the best practices to follow when you use Outlook to manage your appointments and meeting requests. These articles are user-ready documents that can be provided as a training tool.

Additionally, you may have to contact Microsoft Product Support Services. Information that may be required for a more rapid identification of the cause or for the resolution of your issue is provided.



You may use Outlook on your desktop computer or on your handheld device to initiate, to update, and to acknowledge meeting requests. To troubleshoot issues with missing or duplicate appointments, you must examine both Outlook and Exchange Server.

Troubleshooting may require that you use reporting tools. These reporting tools require the following:

  • Appropriate permissions in the environment.

  • Access to custom or third-party programs.

  • Access to custom or third-party hardware Investigation of custom or third-party programs.

  • Investigation of custom or third-party hardware Information about the product usage that may affect the problem.

This article discusses an outline of the support process and the recommendations for troubleshooting issues with missing or duplicate appointments in Outlook.

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General troubleshooting information

In the initial phases of troubleshooting, we recommend that you analyze the problem in the following manner:

  • Is the problem reproducible? If it is, note the steps to reproduce the problem in detail. Additionally, have the steps to reproduce the problem ready if you contact Microsoft Product Support Services.

  • Is the missing appointment a meeting request, a recurring meeting request, an updated meeting request, or a stand-alone appointment? There may be significant differences in the troubleshooting that is required based on the item type.

  • Is text that is in the Subject box of the meeting or of the appointment known? This can be a critical factor in troubleshooting. For example, this information is important when you examine logs or when you troubleshoot issues with views or when you search for the item in the Deleted Items folder.

  • Is the software version known? Version information may be required to resolve your specific issue or to determine its cause. Information about versions of software that may use the Calendar and meeting requests or about versions of software that may affect the Calendar and meeting requests is required. This software includes Microsoft Outlook, Microsoft Exchange Server, the Cdo.dll files that are being used, and any third-party collaborative software. This information should include installed software updates or hotfixes for the products in question. This is required information if Microsoft Product Support Services is used.

  • Is Deleted Items Recovery enabled for the environment?

  • Do you have the appropriate permissions in the organization for logging for Outlook, for Exchange, or for third-party products. Data from these tools may be requested if you contact Microsoft Product Support Services.

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When you troubleshoot the various components that can make up the environment, the following categories are frequently identified as key troubleshooting areas:

  • Microsoft Outlook

  • Microsoft Exchange Server

  • Collaboration Data Objects (CDO)

  • Third-party software and devices that are used in the environment

Each category is discussed later in the article. When you troubleshoot, simultaneous work on these categories may be required for a more rapid resolution.

Microsoft Outlook troubleshooting

To troubleshoot Outlook, you frequently must examine how it is used. User training and a user-ready "best practices" document are available on the Microsoft Office Assistance Web site. Product Support Services recommends that you review this information and that you provide it to the users of Microsoft Outlook.

For scenario-based and best-practice information, view the following content:

If issues occur with missing or duplicate appointments, standard troubleshooting for Outlook is as follows:

  • Obtain the latest service pack for the version of Outlook that you are using. For example, you can resolve many Microsoft Outlook 2002 issues by obtaining Microsoft Office 2002 Service Pack 3.

  • Use the same version of Outlook on all the clients that access the same Calendar. Later versions of Outlook and later service pack levels may provide resolutions to issues.

  • Verify that the version of Outlook that you are using is currently supported. Updates and service packs are not created for expired product versions.

  • Verify that Deleted Items Recovery is enabled in the environment.

    For more information, see the following article:

    Recover deleted items in Outlook for Windows

  • Troubleshoot all the mailboxes that are involved in the manager-delegate relationship. The number of delegates for a mailbox may have a big effect on troubleshooting. We recommend that you remove delegates temporarily or that you use the smallest possible number of delegates when you troubleshoot.

    Note Unless the delegates are carefully managed, many delegates for a single mailbox may create conflicts or other issues. We recommend that you use the smallest possible number of delegates in typical usage.

  • Accept or decline all meeting items individually. If rules are used to move meeting requests out of the Inbox, tentative meetings will not be entered in the Calendar. If a delegate also receives meeting requests, make sure that the manager and the delegate have a clearly defined process for handling meeting requests.

  • Use the Calendar logging features of Outlook.

    For more information about calendar logging, see the following article:

    841615 Description of the Calendar logging feature in Outlook

For more information about common meeting request issues in Outlook, see the following article:

924470 Outlook delegate feature in mixed versions of Microsoft Outlook and Entourage
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Microsoft Exchange Server troubleshooting

When missing or duplicate meeting requests are reported, the antivirus software that is used to scan the Exchange server mailboxes in the organization should be examined. Troubleshooting information for Exchange Server is available at:

Exchange Server Troubleshooting

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Collaboration Data Objects (CDO)

CDO is frequently involved in issues with missing or duplicated appointments. These issues can include the following:

  • Synchronization with handheld devices or with wireless devices.

  • Programmatic issues when you access the Calendar by using a custom solution.

When you troubleshoot these issues, we generally recommend the following:

  • Make sure that you use the latest CDO version for programs that can modify Appointment items by using CDO. For example, Research In Motion (RIM) Blackberry Enterprise Server can only modify Appointment items by using CDO. Contact Microsoft Product Support Services or search the online support sites referenced above for the latest updates.

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Third-party software and devices

There are several vendors that provide software suites and devices for the purposes of synchronizing with Microsoft Exchange Server. General recommendations for troubleshooting issues with missing or duplicated items in such environments are as follows:

  • Make sure that you use the latest software suites, service packs, hotfixes, and software updates that are available from the vendor.

  • Make sure that the latest CDO update is installed on the server that is running the third-party software suite.

  • Make sure that you use the latest version of the synchronization software for your handheld device.

In environments that run Blackberry Enterprise Server, we recommend the following:

Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information.

  • Obtain Blackberry Enterprise Server updates and handheld synchronization software updates.

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Devices that use Microsoft Exchange ActiveSync

Exchange ActiveSync (EAS) allows devices to synchronize the Inbox, Calendar, and other items with Microsoft Exchange Server mailboxes. For more information on known issues that may cause missing or duplicate appointments when using EAS devices, click the following article number to view the article in the Microsoft Knowledge Base:

2563324 Current issues with Microsoft Exchange ActiveSync and Third Party Devices back to the top

Information that is required when you contact Microsoft Product Support Services

The following list of items that are typically requested by support engineers is a guideline. Every case is unique and may require different information. Having this information early on will greatly help the support engineer in providing a faster resolution.

  • When did the problem start occurring?

  • What changed, if anything, in the organization at the time the issue started occurring?

  • How frequently does the problem occur?

  • How many users are affected?

  • What is the version number of the Store.exe file that is on the Exchange Servers in the organization?

  • What is the version number of the Cdo.dll file that is on the computer that is running the software suites for synchronization with Exchange Server? These software suites include Blackberry Enterprise Server, GoodLink, and others.

  • If a CDO program is used in the environment, what is the version of the Cdo.dll file that the program uses? This may require discussion with the software developer.

  • What Outlook add-ins and COM add-ins are installed on your computer? The add-ins that are installed can affect your computer. Note which are enabled and which are disabled.

  • Is Outlook running in Cached Exchange Mode for Outlook 2003, or is it in a primarily Offline configuration for Outlook 2002 and for earlier versions?

  • Are any handheld devices (PDA’s) being used? If they are, include the manufacturer information, the synchronization software that is used, and the version number.

  • Is server antivirus software configured to exclude drive M? This applies to Exchange 2000 Server or to Exchange Server 2003 if drive M has been displayed.

  • Are the EXCHSRVR directory contents being scanned by the antivirus?

  • Are delegates used by the impacted user? If delegates are used, include the number of delegates and the exact delegate permissions.

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