Hi AllWe are running Exchange 2003 SP2 with Outlook 2003/2007 clients. We are also in the process of migrating to Exchange 2007 - the servers are in place in the existing org, we will begin mailbox moves shortly. And we also have Blackberry 4.1.6 servers.I have noticed the following Event ID's in the Exchange 2003 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.There is a correlating Technet article here:http://support.microsoft.com/kb/969254Here is the suggest resolution: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://support.microsoft.com/kb/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. I've checked the version of our Exdco.dll file and it's greater than 6.5.7653.5So - given that we have Blackberry *and* Exchange 2007 in our environment, do we need to apply the Hotfix in http://support.microsoft.com/kb/938650/, or - given that this Event ID only seems to affect one user, would it be better to ignore the warnings given that we will shortly be moving to Ex07?Any advice appreciated!

Hi,I recommend you to finish migation and then check the issue again.Regards,Xiu