purgeGmail.gs

// Modified from: http://www.labnol.org/internet/gmail-auto-purge/27605/

// Labels to support
// Delete after 15 days
// Delete after 30 days
// Delete after 90 days
var days = [15,30,90];

function Intialize() {
  return;
}

function Install() {
  ScriptApp.newTrigger("purgeGmail").timeBased().everyDays(1).create();
}

function Uninstall() {
  
  var triggers = ScriptApp.getScriptTriggers();
  for (var i=0; i<triggers.length; i++) {
    ScriptApp.deleteTrigger(triggers[i]);
  }  
}
function purgeGmail(purge) {
  
  days.forEach(function(purge) {
    var label = "delete-after-" + purge + "-days";    
    
    
    var age = new Date();  
    age.setDate(age.getDate() - PURGE_AFTER);    
    
    var purge  = Utilities.formatDate(age, Session.getScriptTimeZone(), "yyyy-MM-dd");
    var search = "label:\"" + label + "\" before:" + purge;
    
    try {
      var threads = GmailApp.search(search, 0, 500);
      for (var i=0; i<threads.length; i++) {
        var messages = GmailApp.getMessagesForThread(threads[i]);
        for (var j=0; j<messages.length; j++) {
          var email = messages[j];       
          if (email.getDate() < age) {
            email.moveToTrash();
          }
        }
      }
      
    } catch (e) {}
  });
  
}