To override the Content-type in your clients, use the HTTP Accept Header, append  the .json suffix or  ?format=json
To embed the response in a jsonp callback, append ?callback=myCallback
        
        HTTP + JSON
         The following are sample HTTP requests and responses. 
            The placeholders shown need to be replaced with actual values.
POST /DynamicsCRM/Email HTTP/1.1 
Host: data.regent-college.edu 
Accept: application/json
Content-Type: application/json
Content-Length: length
{"guid":"String","gmail_thread_index":"String"}
 
HTTP/1.1 200 OK
Content-Type: application/json
Content-Length: length
{"guid":"String","gmail_thread_index":"String","subject":"String","changed_date":"0001-01-01T00:00:00.0000000"}