Hi Mario, that } was by mistake. I have corrected as suggested and checked but still, it is showing bad request message. I tried without any payload and the result was {"requestError":{"serviceException":{"messageId":"BAD_REQUEST","text":"[from : may not be null, content : must contain at least one of these (text, html or templateId), to : size must be between 1 and 2147483647, subject : may not be null]"}}} As the User is able to authenticate the request, I guess the problem is with payload only. Regards, ... View more