I recieved the following error just twice, back to back in the event log in the last week.. Event Type: Error Event Source: EXCDO Event Category: General Event ID: 8217 Date: 12/31/2011 Time: 1:45:08 PM User: N/A Computer: Mailserver Description: The processing of the recurring appointment with the subject "XXXXX" in mailbox: XXXX failed with error code 0x80004005. This appointment will not be visible in the web client or other non-MAPI client. For more information, click http://www.microsoft.com/contentredirect.asp. Last time I was seeing these errors it was happing daily which is why I updated the excdo.dll file and the problem went away..so seeing the two new errors concerns me. Any suggestions? System Specs: Exchange Server 2003 SP2. Workstations are Outlook 2007

You could find the appointment and delete and recreate it.Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

Hi Phill, Please refer to this KB: http://support.microsoft.com/kb/969254 Hope it helps.Rowen TechNet Community Support

Thanks for your reply. I did see the article that you listed however our small organization only has a single exchange 2003 server. There is no exchange 2007. The excdo.dll file was already updated awhile back to version 6.5.7654.12. A bit concerned here..when I looked at the regedit I did not see this key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\EXCDO\Parameters I see Microsoft but no EXCDO Am I correct that key only needs to exist if I want to "poof"? What am I do now? Any suggestions? Is it possible just those two appointments are bad?

Hi Phill, It is possible, you can delete those bad items firstly as Ed suggested. Thanks.Rowen TechNet Community Support

You could find the appointment and delete and recreate it.Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

Hi, Any update?Rowen TechNet Community Support

I had worked with MS back in 2009/2010 on this very issue, sent them logs and never could get a fix. It's been happening ever since and no one has had any issues with appts/reminders/etc. http://forums.msexchange.org/m_1800511408/mpage_1/key_/tm.htm#1800515063