Automatically sends Gmail drafts with specific label.

AutoSendDraft.gs

/*
 * Inspired by: http://stackoverflow.com/a/27215474
 *
 * After copying the code to your own script, open Resources -> Advanced Google Services,
 * 1. enable Gmail API (switch to "on"),
 * 2. open the link for the Google Developers Console, and enable the Gmail API for your project.
*/

function sendMorningDrafts() {
  sendLabeledDrafts("schedule/send-next-0700-0800");
}

function sendEveningDrafts() {
  sendLabeledDrafts("schedule/send-next-1800-1900");
}

function sendLabeledDrafts(label_to_send){
  var drafts = GmailApp.getDrafts();
  if (!drafts) { return; }  // No draft exists.
  
  for (var i=0; i<drafts.length; i++) {
    var draft = drafts[i];
    var thread = draft.getMessage().getThread();
    var sent_flag = false;
    
    var labels = thread.getLabels();
    for (var j=0; j<labels.length; j++) {
      var label = labels[j];
      
      if (label.getName() === label_to_send) {
        var response = draft.send();
        var sent_flag = true;
        var new_thread = response.getThread();
        new_thread.removeLabel(label);  // remove label not to send the same message again.
      }
      if (sent_flag) { break; }
    }
    if (sent_flag) { continue; }
  }
}