// Credit: https://gist.github.com/rboyd/5027691

function deleteLongEmails() {
  var WORDLIMIT = 100;

  // Process only new emails in inbox that have not been read and receive in the last day
  var threads = GmailApp.search('to:me is:unread in:inbox newer_than:1d');

  for (var i = 0; i < threads.length; i++) {
    // Ignore email conversations
    if (threads[i].getMessageCount() == 1) {
      var msg = threads[i].getMessages()[0];
      var word_count = msg.getPlainBody().split(' ').length;

      if (word_count > WORDLIMIT) {
        msg.reply('Your email is too long. Please resend after editing it to less than 100 words.');
        GmailApp.moveThreadToArchive(threads[i]);
      }
    }
  }
}