async function sendSurveyEmail(email, name) {
  const mailOptions = {
    from: '"MyCoolApp" <noreply@firebase.com>',
    to: email,
    subject: 'How did you like our new app?',
    text: `Hey ${name}, We've seen that you have upgraded to the new version of our app!
           It would be awesome if you could tell us how you like it.
           Fill out our survey: ${LINK_TO_SURVEY}`,
  };

  await mailTransport.sendMail(mailOptions);
  functions.logger.log('Upgrade App Survey email sent to:', email);
}
Sends an email pointing to the Upgraded App survey.