Example

var data = new FormData();
data.append("from_name", "Thaksinai Kondee");
data.append("from_email", "thaksinai@hotmail.com");
data.append("to", "thaksinai@ispio.com");
data.append("subject", "ร่วมฉลอง ครบรอบการก่อตั้ง บริษัท Nipa technology วันนี้ เวลา 18:00 น.");
data.append("message", "content1");
data.append("reply_email", "se55660159@gmail.com");
data.append("reply_name", "Thakweb.com");

var xhr = new XMLHttpRequest();
xhr.withCredentials = true;

xhr.addEventListener("readystatechange", function () {
  if (this.readyState === 4) {
    console.log(this.responseText);
  }
});

xhr.open("POST", "https://app-x.nipamail.com/v1.0/transactional/post?accept_token=NPAPP-IGBmfucf0Np567WzwAH1KuRovnszt9r4HJPJ2U4SRhPk1pCeBXEi7nUkixLby8qwwwymbXwtV3gjOMeodNKlcAChYrZ0D8TQv60208fxXIZlJ7www");
xhr.setRequestHeader("cache-control", "no-cache");

xhr.send(data);