Gmail Auto-Forward Starred Emails

forwardAndLabelStarredEmails.gs

FORWARD_DEST="forward_address@example.com"

function forwardAndLabelStarredEmails() {
  var laterLabel = GmailApp.getUserLabelByName("@later");
  if (!laterLabel) {
    laterLabel = GmailApp.createLabel("@later");
  }

  var threads = GmailApp.search('is:starred');
  var emailParts = Session.getActiveUser().getEmail().split('@')[1].split('.');
  var accountDomain = emailParts[0].charAt(0).toUpperCase() + emailParts[0].slice(1).toLowerCase();

  for (var i = 0; i < threads.length; i++) {
    var messages = threads[i].getMessages();
    for (var j = 0; j < messages.length; j++) {
      var message = messages[j];

      if (message.isStarred()) {
        var messageId = message.getId();
        var gmailLink = "https://mail.google.com/mail/u/0/#all/" + messageId;
        var subject = "要処理[" + accountDomain + "] " + message.getSubject();
        var body = "<div>" + gmailLink + "</div>&nbsp;<br>" + message.getBody();

        GmailApp.sendEmail(FORWARD_DEST, subject, "", {
          htmlBody: body
        });

        threads[i].addLabel(laterLabel);
        message.unstar();
      }
    }
  }
}