"This meeting is not in the calendar; it may have been moved or deleted." Outlook error

When you try to accept a meeting request in Microsoft Office Outlook 2007 or in Microsoft Outlook 2010, the information bar displays the following error message:

This meeting is not in the calendar; it may have been moved or deleted.

Additionally, you notice that the meeting does not appear as "Tentatively Accepted" in your calendar.

The AutomateProcessing calendar setting for your Microsoft Exchange Server 2007 or Microsoft Exchange Server 2010 mailbox is set to None.

The Exchange Server administrator must start the Exchange Management Shell on the Exchange mailbox server. Then, run the following command in the Exchange Management Shell:

Exchange Server 2007:

Set-MailboxCalendarSettings username -AutomateProcessing Autoupdate

Exchange Server 2010:

Set-CalendarProcessing username -AutomateProcessing AutoUpdate

Where username is the affected user's alias.

For more information about changing the AutomateProcessing argument on multiple mailboxes at the same time, click the following article number to view the article in the Microsoft Knowledge Base:

959960 All e-mail messages for some users may be put in the deleted items folder