Gmail Life Saver

code.js

function archiveInbox() {
  var query = 'label:inbox is:read older_than:28d -label:unanswered -label:unread';
  var batchSize = 100;
  
  while(GmailApp.search(query, 0, 1).length == 1) {
    GmailApp.moveThreadsToArchive(GmailApp.search(query, 0, batchSize));
  }
}