Email sending example using rendered HTML in appscript

email.js

function renderEmail(context) {
  var template = HtmlService.createTemplateFromFile("emailTemplate");
  template.context = context;
  return template.evaluate().getContent();
}

function sendEmail(order) {
  var context = {
    message: "Your order has been accepted! Please find the details as follow:",
    customerName: order[1],
    status: order[2],
    deliveryDate: order[3]
  }
  var emailAddress = order[0];
  var emailSubject = "Your order has been accepted!";
  var emailBody = renderEmail(context);
  MailApp.sendEmail({
    to: emailAddress,
    subject: emailSubject,
    htmlBody: emailBody
  });
}

function sendCustomerNotification() {
  var order = [
    "[email protected]",
    "John Doe",
    "Accepted",
    "23 June 2019"
  ];
  sendEmail(order);
}