Microsoft Exchange Server 2003 users who use Outlook Web Access (OWA) or Exchange ActiveSync devices may notice that some meetings may not appear in their OWA or ExchangeActiveSync device calendars. However, the meetings will appear in their calendars if they use any version of an Outlook Client. Additionally, EXCDO events that resemble the following event may appear in the Exchange 2003 computer's application event log:

Event Type: Error
Event Source: EXCDO
Event Category: General
Event ID: 8217
Description: The processing of the recurring appointment with the subject "subject" in mailbox: user_name failed with error code 0x80004005. This appointment will not be visible in the web client or other non-MAPI client.

This error occurs if a PT_SYSTIME value on a calendar item cannot be converted from MAPI format to MIME format by using the VariantTimeToSystemTime function. This can occur if there is a corrupted property on the message or an invalid property on the message.

To prevent this error, take the following actions:

• Make sure that the Excdo.dll file on the Exchange server is version 6.5.7653.5 or a later version. To obtain this version of the Excdo.dll file, see Microsoft Knowledge Base article 938650. This article describes similar mail delivery issues between Exchange 2003 and Exchange 2007. Or, you can apply any later Excdo update. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
  938650  (http://kbalertz.com/Feedback.aspx?kbNumber=938650/ ) A meeting update message or a meeting cancellation message from an Exchange 2003 user is not delivered to an Exchange 2007 user
  
  Note If Blackberry is in the mail environment, the CDO components have to be updated because the hotfix that is mentioned in Microsoft Knowledge Base article 938650 updates Collaboration Data Objects (CDO) versions.
• Install the hotfix that is mention in Microsoft Knowledge Base article 938650 and add the FixRecipientTrackStatusTime registry entry.
  
  Note You must restart the Information Store service for this registry key to take effect.

What to do with previously failed expansions

The hotfix and registry entries that are mentioned here will address the problem going forward. However, Calendar items that are already in this affected state have to be expanded again to be visible in OWA. "Poof" is a process that will delete all the cached expansions and perform the expansions again.
To force the deletion of these cached expansions on a user’s calendar, follow these steps:

1. Set the CalendarRecovery registry value to 1 on the Exchange 2003 computer. To do this, follow these steps:
   1. Click Start, click Run, type regedit in the Open box, and then click OK.
   2. Locate and then click the following registry subkey:
      HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\EXCDO\Parameters
      Note If the registry subkeys EXCDO and Parameters do not exist, go to step c. Otherwise, go to step e.
   3. On the Edit menu, click Add Key, type EXCDO, and then press ENTER.
   4. On the Edit menu, click Add Key, type Parameters, and then press ENTER.
   5. On the Edit menu, point to New, click DWORD Value, type CalendarRecovery, and then press ENTER.
   6. Double-click CalendarRecovery, type 1 in the Value data box, click Decimal, and then click OK.
   7. Exit Registry Editor.
   Note Exchange Services does not have to be restarted for this registry key to be reread.
2. Start Outlook on the client computer.
3. Right-click the Calendar folder, and then click Properties.
4. Click the General tab, type CleanupExpansionCachesInTheCalendarFolder in the Description box, and then click OK.
5. If the Description box already includes CleanupExpansionCachesInTheCalendarFolder, clear the Description field, click Apply, type CleanupExpansionCachesInTheCalendarFolder in the Description field, and then click OK.
   Note This signals Exchange to perform the Poof for this calendar.

If you want to Poof more than one calendar at a time, use MAPI utility that is described on the following Microsoft Web site:

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.