The JSON-RPC endpoint
"http://mail.yahooapis.com/ws/mail/v1.1/jsonrpc"and it implements the JSON-RPC spec on top of the Web service.
method: name of the API method being called.
params: an array containing the method parameters.
id(optional): the ID of the request, allows asynchronous clients to match a response back up with the original request.
result: the return from the API method, must be null if there was an error.
error: an error object resulting from the call being made (like an exception), must be null if there was no error.