Automate sending mass Emails using Gmail UI

gmail-send.js

function simulateClick(el) {
  var evt = document.createEvent("MouseEvents");
  evt.initMouseEvent("click", true, true, window,
    0, 0, 0, 0, 0, false, false, false, false, 0, null);
  var cb = el;
  var canceled = !cb.dispatchEvent(evt);
}
function getElementByXpath(path) {
  return document.evaluate(path, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
}
function mouseEvs(el){
  const mouseDownEv = new MouseEvent('mousedown');
  el.dispatchEvent(mouseDownEv)
  const mouseUpEv = new MouseEvent('mouseup');
  el.dispatchEvent(mouseUpEv)
}

function sendEmail() {
  composeBtn = getElementByXpath('//*[text()="Compose"]')
  mouseEvs(composeBtn)

  setTimeout(() => {
    toField = getElementByXpath('//span[text()="To"]/ancestor-or-self::td/following-sibling::td//textarea')
    toField.innerText = contacts[contactIndex].email
    subjectField = document.querySelector('[name="subjectbox"]')
    subjectField.value = subject
    bodyField = getElementByXpath('//span[text()="To"]/ancestor-or-self::form/following-sibling::table//div[@contenteditable="true"]')
    bodyField.innerHTML = getBody(contacts[contactIndex].name)

    setTimeout(() => {
      simulateClick(getElementByXpath('//div[text()="Send"]')) // hit send

      if (contacts[contactIndex + 1]) {
        contactIndex++
        setTimeout(sendEmail, 3000)
      }
    }, 1000)
  }, 3000)
}

contacts = [{
  email: 'check-out@courgette-testing.com',
  name: 'Courgette Testing',
},{
  email: 'check-out@courgette-testing.com',
  name: 'Courgette Testing',
}]

subject = 'Courgette Testing Rocks! Please star the github if you like it!'

getBody = (name) => `Hi ${name}

Testing 123

Regards
Alex
`.replace(/\n/g, '<br />')


sendEmail()