refer owa(exchange) 2013 via a iframe in sharepoint 2013

Refused to display 'https://cas.temp.local/owa/' in a frame because it set 'X-Frame-Options' to 'SAMEORIGIN'.

create a file named a.cs under C:\Program Files\Microsoft\Exchange Server\V15\FrontEnd\HttpProxy\owa\app_code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Security;
using System.Security.Principal;

namespace ZY
{
public class M1 : IHttpModule
{

public void Dispose()
{

}

public void Init(HttpApplication application)
{
application.PreSendRequestHeaders += new EventHandler(application_PreSendRequestHeaders);

}

void application_PreSendRequestHeaders(object sender, EventArgs e)
{
HttpApplication application = (HttpApplication)sender;
application.Context.Response.Headers.Set("X-Frame-Options","");
application.Context.Response.Headers.Remove("X-Frame-Options");
}

}
}

add a line to web.config(C:\Program Files\Microsoft\Exchange Server\V15\FrontEnd\HttpProxy\owa)

between

<system.webServer>
<serverRuntime uploadReadAheadSize="0" />
<modules>

<add name="zy" type="ZY.M1" />

</modules>

close web browser ,clear cache and cookies

The OWA 2013 now can display with a iframe under a differetn subdomain