Gmail auto-responder for use in https://script.google.com

AutoResponder.js

function AutoResponder(e) {

  // Our email account that will be recieving:
  var email_account = "testemail@gmail.com";
  // Search for subject:
  var subject       = "testsubject";

  // Send our response email
  var threads = GmailApp.search("subject:(" + subject + ") label:unread to:(" + email_account + ")");
  for (var i = 0; i < threads.length; i++) {

    // This is where further logic would go
    var msg = threads[i].getMessages()[0];
    var word_count = msg.getBody().split(' ').length;

    //Our response
    var response_body = "Hey there, this is a test auto-responder.<br>\
    Number of words: " + word_count + "<br>\
    Original body: " + msg.getBody();
    // Respond to email
    threads[i].reply("", {htmlBody: response_body, from: email_account});
  }

  // Mark all as read
  var threads = GmailApp.search("subject:(Contact Form) label:unread to:(" + email_account + ")");
  GmailApp.markThreadsRead(threads);
}