https://www.it-connect.fr/configurer-postfix-pour-envoyer-des-mails-avec-gmail/

https://myaccount.google.com/apppasswords

https://script.google.com

function emptyTrash() {
  var gmailSearchString = `in:trash`

  var threads = GmailApp.search(gmailSearchString);
  const n = threads.length;
  if (n <= 0) {
    Logger.log("No threads matching search string \"%s\"", gmailSearchString);
    return
  } else {
    Logger.log("%s threads matching action **%s**", n, gmailSearchString);
  }

  for (var i = 0; i <threads.length; i++) {
    var thread = threads[i];
    Logger.log(`\t Thread# ${i} [ID: ${thread.getId()}]: [message : ${thread.getFirstMessageSubject()}] deleted`);
    Gmail.Users.Threads.remove('me', thread.getId());
  }
}

function toTrash() {
  var gmailSearchString = `to:me`

  var threads = GmailApp.search(gmailSearchString);
  const n = threads.length;
  if (n <= 0) {
    Logger.log("No threads matching search string \"%s\"", gmailSearchString);
    return
  } else {
    Logger.log("%s threads matching action **%s**", n, gmailSearchString);
  }

  for (var i = 0; i <threads.length; i++) {
    var thread = threads[i];
    Logger.log(`\t Thread# ${i} [ID: ${thread.getId()}]: [message : ${thread.getFirstMessageSubject()}] deleted`);
    thread.moveToTrash();
  }
}

Trigger pour automatiser: https://wasteofserver.com/permanently-delete-unwanted-emails-from-gmail-out-of-sight-out-of-mind/