You cannot forward an external meeting request in an Exchange Server 2013 environment

When a Microsoft Exchange Server 2013 mailbox user tries to forward a meeting request that is from an external sender, Outlook Web App displays the following error message, and the user cannot forward the meeting request:
If the user sends the meeting request by using Microsoft Outlook, the user receives a non-delivery report (NDR) that contains the following information:

This issue occurs because the SendAs check encounters an exception.

To resolve this issue, install the following cumulative update: 

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.