Unable to Delete Email from Outlook Web App 2010

A customer of mine cannot delete emails from Outlook Web App (OWA) 2010.  The customer is running Exchange 2010 SP2 with UR1.  When deleting an email the following error is experianced in OWA:

An unexpected error occured and your request couldn't be handled.

Also whenever the error occurs in Outlook Web App the following errors are logged to the Application Log of the server.

Outlook Web App couldn't connect Exchange Web Services due to a configuration error. Response code = "500".

WebHost failed to process a request.
 Sender Information: System.ServiceModel.ServiceHostingEnvironment+HostingManager/20974680
 Exception: System.ServiceModel.ServiceActivationException: The service '/EWS/exchange.asmx' cannot be activated due to an exception during compilation.  The exception message is: A binding instance has already been associated to listen URI 'http://tst-dc1-cas-1.tsthosting.local/EWS/Exchange.asmx'. If two endpoints want to share the same ListenUri, they must also share the same binding object instance. The two conflicting endpoints were either specified in AddServiceEndpoint() calls, in a config file, or a combination of AddServiceEndpoint() and config. . ---> System.InvalidOperationException: A binding instance has already been associated to listen URI 'http://tst-dc1-cas-1.tsthosting.local/EWS/Exchange.asmx'. If two endpoints want to share the same ListenUri, they must also share the same binding object instance. The two conflicting endpoints were either specified in AddServiceEndpoint() calls, in a config file, or a combination of AddServiceEndpoint() and config.
   at System.ServiceModel.Description.DispatcherBuilder.InitializeServiceHost(ServiceDescription description, ServiceHostBase serviceHost)
   at System.ServiceModel.ServiceHostBase.InitializeRuntime()
   at System.ServiceModel.ServiceHostBase.OnOpen(TimeSpan timeout)
   at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout)
   at System.ServiceModel.ServiceHostingEnvironment.HostingManager.ActivateService(String normalizedVirtualPath)
   at System.ServiceModel.ServiceHostingEnvironment.HostingManager.EnsureServiceAvailable(String normalizedVirtualPath)
   --- End of inner exception stack trace ---
   at System.ServiceModel.ServiceHostingEnvironment.HostingManager.EnsureServiceAvailable(String normalizedVirtualPath)
   at System.ServiceModel.ServiceHostingEnvironment.EnsureServiceAvailableFast(String relativeVirtualPath)
 Process Name: w3wp
 Process ID: 4516

After investigating I found the problem was with Exchange Web Services in the web.config file located under:

C:\Program Files\Microsoft\Exchange Server\V14\ClientAccess\exchweb\ews

This particular client had an F5 Load Balancer and required that SSL Offloading was configured in the Exchange environment.  We had followed Microsoft's instructions for configuring SSL offloading on Exchange 2010 which are documented here:

http://social.technet.microsoft.com/wiki/contents/articles/1267.how-to-configure-ssl-offloading-in-exchange-2010-en-us.aspx

This article instructs customers to do a find and replace on the EWS web.config file to replace all instances of "httpsTransport" with "httpTransport".  However as of Exchange 2010 SP1 the web.config file contains both the httpTransport and httpsTransport settings in the XML configuration file so this is no longer required.

I went back and changed the httpTransport occurances to httpsTransport to ensure the config file accomodated both HTTP and HTTPS.