When you use Microsoft Office Outlook 2003 in online mode to access your mailbox in a Microsoft Exchange Server 2010 environment, you may be unable to open the message item. Additionally, you receive the following error message:
Can't open this item.
Note This issue typically occurs when the message item contains many recipients and the message status is unread.
This issue occurs because the Exchange Server 2010 server adds the RopNotify remote operation (ROP) response after the RopBufferTooSmall response when it detects that the remote procedure call (RPC) buffer is insufficient. Then, Outlook 2003 resends the data that is followed by the RopNotify response. However, the Exchange Server 2010 server does not expect the RopNotify response and returns the ecRpcFormat error code.
To resolve this issue, install the following update rollup:
2645995 Description of Update Rollup 1 for Exchange Server 2010 Service Pack 2
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about the RopBufferTooSmall response, visit the following Microsoft website: