purge gmail when out of space

code.gs

// purge gmail script
// i've been using this for years to keep gmail from going over the limit
// it has gotten me from 99% to 50% many times on various accounts
//
// it runs on google apps script, which is google's script platform that can access your email
// to automatically delete older messages according to the rules below
//
// it's controlled by the CONFIG array
// set an age (required)
// set a label or from (one of them is required)
// messages will be searched by label or from address, and messages older than age will be deleted
// they will be deleted in chunks of CHUNK_SIZE and (if you run the Install function) the purge will be run every INTERVAL_MINUTES
//
//
// set the CONFIG variable
// then run the purgeGmail function
// then check your GMail trash and/or View => Logs
// when you're happy with the CONFIG, run the Install function
//
//
// adapted from https://ctrlq.org/code/19383-bulk-delete-gmail

var CONFIG = [
  {"age": "90", "label":"coupons/offers"},
  {"age": "600", "from":"noreply"},
  {"age": "600", "from":"no-reply"},
  {"age": "600", "from":"donotreply"}
];

// this is how often to run the purge, in minutes
var INTERVAL_MINUTES = 5;

// the number of messages to search for and delete each time the script is run
// sometimes Google gives you errors related to resources consumed.  100 usually works if CONFIG has a couple items.  lowering this may help stop that error.
var CHUNK_SIZE = 100;

// sometimes Google gives you errors related to resources consumed.
// at one point, sleeping for 100 to 500 millseconds helped stop that error
var SLEEP_BETWEEN_DELETES = 100;

// sometimes Google gives you errors related to resources consumed.
// at one point, exiting if messages were deleted by one rule helped stop that error
// i.e. if the first rule returns messages, exit. otherwise try second rule
var BREAK_LOOP_IF_MESSAGES_FOUND = false;

function Install() {
  // delete all triggers
  // then set a weekly trigger to reinstall to ensure it is always running
  // then set a minutes trigger to purge on an ongoing basis
  
  deleteAllTriggers();

  var weeklyTrigger = ScriptApp.newTrigger("Install")
           .timeBased().onWeekDay(ScriptApp.WeekDay.MONDAY).atHour(0).create();

  Logger.log("created weekly install trigger: " + weeklyTrigger.getUniqueId());

  var minutesTrigger = ScriptApp.newTrigger("purgeGmail")
           .timeBased().everyMinutes(INTERVAL_MINUTES).create();

  Logger.log("created " + INTERVAL_MINUTES + "-minute purge trigger: " + minutesTrigger.getUniqueId());
}

function Uninstall() {
  deleteAllTriggers();
}

function deleteAllTriggers() {
  // Locate a trigger by unique ID
  var allTriggers = ScriptApp.getProjectTriggers();
  // Loop over all triggers
  for (var i = 0; i < allTriggers.length; i++) {
    var triggerId = allTriggers[i].getUniqueId();
    Logger.log("deleting trigger: " + triggerId);
    ScriptApp.deleteTrigger(allTriggers[i]);
  }
}

function purgeGmail() {
  Logger.log("started");
  var totalDeleted = 0;
  
  // Loop over the configuration
  for (var i = 0; i < CONFIG.length; i++) {
    var item = CONFIG[i];

    var age = new Date();  
    age.setDate(age.getDate() - item.age);    
  
    var purge  = Utilities.formatDate(age, "GMT", "yyyy-MM-dd");
    var search = "";
    if (item.hasOwnProperty('age')) {
      if (item.hasOwnProperty('label')) {
        search += " label:" + item.label;
      } else if (item.hasOwnProperty('from')) {
        search += " from:" + item.from;
      } else {
        Logger.log("could not understand this item.  'age' is required.  either 'label' or 'from' must be specified: " + JSON.stringify(item));
        continue;
      }
      search += " before:" + purge;
    } else {
      Logger.log("could not understand this item.  'age' is required.  either 'label' or 'from' must be specified: " + JSON.stringify(item));
      continue;
    }
   
    Logger.log("going to look for emails using: " + search);
    var threads = GmailApp.search(search, 0, CHUNK_SIZE);
    Logger.log("searched and found: " + threads.length);

    // if anything was deleted, break the loop to reduce resources
    // eventually it will be zero, and the next one can be checked
    // eventually they will all be purged (it can take days or weeks if there are GBs of emails)    
    for (var t=0; t<threads.length; t++) {
      var messages = GmailApp.getMessagesForThread(threads[t]);
      if(messages != null && messages.length>0){
        var email = messages[0];       
        if (email.getDate() < age) {
          Logger.log("moved to trash: " + email.getSubject().substring(0,15) + '... dated ' + Utilities.formatDate(age, email.getDate(), "yyyy-MM-dd"));
          threads[t].moveToTrash();
          totalDeleted++;
        }
      }
      Utilities.sleep(SLEEP_BETWEEN_DELETES);
    }
      
    if (BREAK_LOOP_IF_MESSAGES_FOUND == true && threads.length > 0) {
      Logger.log("going to exit now to save resources");
      break;
    } else if (i < CONFIG.length-1) {
      Logger.log("going to continue");
    }
  }
  
  Logger.log("finished. " + totalDeleted + " messages deleted");
}