Clean GMail

Clean GMail.js

// This script retrieves contents of Gmail Inbox and leaves only
// predefined amount of last messages. Old messages will be
// moved to archive.

function cleanOld(){
  var old_threads = GmailApp.getInboxThreads();
  var leave = 30;
  
  if (old_threads.length>=leave){
    for (var i=leave; i<old_threads.length; i++){
      if (!old_threads[i].isImportant()){
        old_threads[i].moveToArchive();
      }
    }
  }
}