Automate Gmail With App Scripts

Automate Gmail with Google Apps Scripts, which can be used to help keep your inbox clean, autorespond to emails, and many other use cases.

This particular sample script evaluates all threads in the inbox, applies a label "Decaying" to any messages over 14 days old, and applies a label "Auto-Archived" and archives any threads older than 28 days, removing them from the inbox.

Set a trigger for the script under the app script project settings. Recommend scheduling every day at midnight.

function inbox_ager() {
  function getLabel(labelName) {
    let label = GmailApp.getUserLabelByName(labelName);

    if (label == null) {
      GmailApp.createLabel(labelName);
      label = GmailApp.getUserLabelByName(labelName);
    }

    return label;
  }

  function daysAgo(days) {
    let date = new Date();
    date.setDate(date.getDate() - days);

    return date;
  }

  let decayLabel = getLabel("Decaying");
  let archiveLabel = getLabel("Auto-Archived");

  let twoWeeks = daysAgo(14);
  let fourWeeks = daysAgo(28);

  GmailApp.getInboxThreads().forEach((t) => {
    if (t.getLastMessageDate() < fourWeeks) {
      t.removeLabel(decayLabel);
      t.addLabel(archiveLabel);
      t.moveToArchive();
    } else if (t.getLastMessageDate() < twoWeeks) {
      t.addLabel(decayLabel);
    }
  });
}

Inspired by article at Nethunt