Consider the following scenario:
You use a Microsoft Exchange Web Services (EWS) client application to access items in a Microsoft Exchange Server 2010 environment. For example, you use Microsoft Entourage for Mac or Microsoft Outlook for Mac 2011.
The EWS client application uses the GetItem operation in EWS to obtain the MimeContent property of an item. This causes the content conversion of the item to MIME.
The content conversion fails. For example, the item is an invalid iCal.
In this scenario, EWS drops the TCP connection to the client application without any error message. When this occurs, the EWS client application does not receive new items.
This issue occurs because EWS does not handle the content conversion failure that occurs when EWS tries to obtain the MimeContent property of items from the Exchange store.
To resolve this issue, install the following update rollup package:
2608646 Description of Update Rollup 6 for Exchange Server 2010 Service Pack 1
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.