We have seen several of these events on our CAS/HT after installing Rollup 2 for Exchagne 2007 SP1. Event Type: Error Event Source: .NET Runtime 2.0 Error Reporting Event Category: None Event ID: 5000 Date: 6/27/2008 Time: 9:32:13 AM User: N/A Computer: EX-CAS2 Description: EventType clr20r3, P1 microsoft.exchange.imap4.exe, P2 8.1.278.2, P3 481f7feb, P4 microsoft.exchange.imap4, P5 8.0.0.0, P6 481f7feb, P7 a6, P8 17, P9 system.nullreferenceexception, P10 NIL. This error corresponded to a client connecting via OS X Mail and getting the following message: Exchange 2007 IMAP4 server failed to retrieve the following message:Subject: *****From: ******Sent Date: 6/27/2008 9:31:34 AMThe message could not be retrieved using the IMAP4 protocol. The message has not been deleted and may be accessible using either Microsoft Outlook or Microsoft Office Outlook Web Access. You can also try contacting the original sender of the message to find out about the contents of the message.Retrieval of this message will be retried when the server is updated with a fix that addresses the problem. This only seems to happen with calendar requests but I have not been able to reproduce. Any ideas?

Hi, First please check whether event 1020 has been logged in the event log. Then please try to use the below cmdlt to disable calendar processing on this mailbox to see whether event 5000 will be logged again.Get-mailbox | set-mailboxcalendarsettings -AutomateProcessing None Besides, which OS is the client machine hosting? what is OS X Mail? More information share with you: Set-MailboxCalendarSettings http://technet.microsoft.com/en-us/library/aa996340.aspx Best regards, Xiu

Yes event 1020occurs about one minuteafter event 5000 and then event 1000 is logged. This error is not specific to our environment. There are two other cases reported at forums.msexchange.org. The user is running Mac OS X and Apple Mail (OSX Mail) and uses OWA for calendaring. Event Type: Information Event Source: MSExchange IMAP4 service Event Category: ProcessManager Event ID: 1020 Date: 6/27/2008 Time: 9:33:09 AM User: N/A Computer: EX-CAS2 Description: Worker process with process ID 6444 has exited. Event Type: Information Event Source: MSExchangeIMAP4 Event Category: General Event ID: 1000 Date: 6/27/2008 Time: 9:33:15 AM User: N/A Computer: EX-CAS2 Description: IMAP4 server has started successfully.

I would confirm with you whether you have created several thousands search folders by 3rd party imap search software. Hope it helps.

We are having this issue. Yes I reviewed my event log, we have 5000 and 1000 events. Does disable calendar processing solve the issue? Just for the users mailbox right? Get-mailbox | set-mailboxcalendarsettings -AutomateProcessing None

I'm experiencing this error as well and have yet to find a solution. According to this thread its a known issue with a knowledge base number but I can find no refrences to it.http://forums.msexchange.org/m_1800478155/mpage_1/key_/tm.htm#1800478359Thanks

Microsoft tech support confirmed this as a known issue. There is a hotfix but it isn't included in Rollup 3 and the hotfix was only for Rollup 2. I believe the hotfix will be included in rollup 6. The hotfix is named Exchange2007-KB954237-x64-EN.msp