Gmail: delete old emails automatically

README.md

Gmail: delete old emails automatically

Automatically deletes old emails that match the specified label.

Get started

• Create a new Google Apps Script at https://script.google.com
• Overwrite the placeholder with the javascript below
• Update the following constants:
  • LABEL_TO_DELETE: the label that should be have old messages deleted
  • DELETE_AFTER_DAYS: the age of messsages after which they will be moved to trash
• Save the script, then run:
  • Initialize
  • Install

If you ever want to remove the script, run Uninstall to remove any left over triggers.

Changelog

2017-07-31

• Added support for multiple labels
• Added configurable TRIGGER_NAME
• Increased default page size
• Decreased default delay between receipt and delete

2016-01-21

• Removed use of deprecated Session.getTimeZone()
• Improved efficiency for long threads by checking thread.getLastMessageDate()

Acknowledgements

H/T: Arun's post How to Auto Delete Old Emails In Any Gmail Label

delete-by-label.js

// The name of the Gmail Label that is to be checked for purging?
var LABELS_TO_DELETE = [
  "your-label-here"
];

var TRIGGER_NAME = "dailyDeleteGmail";

// Purge messages in the above label automatically after how many days?
var DELETE_AFTER_DAYS = "60";

var TIMEZONE = "AEST";

// Maximum number of threads to process per run
// Note: this cannot be greater than 500, because Google reasons
var PAGE_SIZE = 500;

// If number of threads exceeds page size, resume job after X mins (max execution time is 6 mins)
var RESUME_FREQUENCY = 7;

// First trigger will run this many minutes after Install function is executed
var INSTALL_DELAY = 2;

/*
IMPLEMENTATION
*/
function Intialize() {
  return;
}

function Install() {

  // First run trigger
  ScriptApp.newTrigger(TRIGGER_NAME)
           .timeBased()
           .at(new Date((new Date()).getTime() + 1000*60*INSTALL_DELAY))
           .create();
}

function Uninstall() {
  
  var triggers = ScriptApp.getProjectTriggers();
  for (var i=0; i<triggers.length; i++) {
    ScriptApp.deleteTrigger(triggers[i]);
  }
  
}

function dailyDeleteGmail() {

  var age = new Date();  
  age.setDate(age.getDate() - DELETE_AFTER_DAYS);    
  
  var purge  = Utilities.formatDate(age, TIMEZONE, "yyyy-MM-dd");
  var search = "(label:" + LABELS_TO_DELETE.join(" OR label:") + ") before:" + purge;
  Logger.log("PURGE: " + purge);
  Logger.log("SEARCH: " + search);
  
  try {
    
    // Google Scripts has a stupid 20 trigger limit, which you can easily exceed if
    // there's a lot of mail that needs deleting. There's also no way that I know of
    // to find out the trigger execution date, name, run status or anything else useful from
    // invoking getProjectTriggers that might allow you to delete expired triggers.
    
    // Therefore, the only thing you can do to guarantee that you will not run out of 
    // triggers is to stupidly delete ALL triggers and recreate the daily trigger.
    // It is dumb, but dumb is the way here.
    
    // Get rid of all triggers
    Uninstall()
    
    // Intstall daily trigger... Sigh.
    ScriptApp.newTrigger(TRIGGER_NAME)
           .timeBased().everyDays(1).create();
    
    var threads = GmailApp.search(search, 0, PAGE_SIZE);
    
    // Resume again in RESUME_FREQUENCY minutes
    if (threads.length == PAGE_SIZE) {
      Logger.log("Scheduling follow up job...");
      ScriptApp.newTrigger(TRIGGER_NAME)
               .timeBased()
               .at(new Date((new Date()).getTime() + 1000*60*RESUME_FREQUENCY))
               .create();
    }
    
    // Move threads/messages which meet age criteria to trash
    Logger.log("Processing " + threads.length + " threads...");
    for (var i=0; i<threads.length; i++) {
      var thread = threads[i];
      
      if (thread.getLastMessageDate() < age) {
        thread.moveToTrash();
      } else {
        var messages = GmailApp.getMessagesForThread(threads[i]);
        for (var j=0; j<messages.length; j++) {
          var email = messages[j];
          if (email.getDate() < age) {
            // Never logs anything... Mysterious... Logs to Narnia?
            Logger.log("Deleting: " + email.getSubject())
            email.moveToTrash();
          }
        }
      }
    }
    
  } catch (e) {
    Logger.log(e);
    throw(e);
  }
}