Assume that you build an Internet Information Services (IIS) module that runs in the same IIS application that uses Microsoft Messaging Application ProgrammingInterface (MAPI) over HTTP. When you try to use the HttpContext.Current.Request.InputStream property to receive the request body, an exception is thrown.
This issue occurs because the MAPI over HTTP protocol is set to use the "Bufferless" ReadEntityBody mode instead of the "Classic" mode when Microsoft Exchange Server 2013 reads a request. Therefore, no results can be provided to the custom IIS module for the MAPI over HTTP protocol.
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.
For more information about the ReadEntityBody mode, see ReadEntityBodyMode Enumeration.
Note We do not recommend running other IIS modules inside the same IIS application as Exchange Server components. You may be asked to remove the custom IIS modules to help in troubleshooting if you open a case with Microsoft Support.