Recipe

Log new Gmail messages to a Google Sheet

Finds mail matching a search, appends date, sender, subject and message ID to a tab, and skips messages already logged.

Set it up

1. Make a tab named Inbox log with headers Date, From, Subject, Message ID.
2. Paste the script, edit the query in GL, and save.
3. Run logMessages and approve the prompts. Add a time-driven trigger to keep it running.

The script

/**
 * Log new Gmail messages that match a search into a sheet, once each.
 * Sheet columns: Date, From, Subject, Message ID. Add a time-driven trigger for logMessages.
 */
var GL = { sheetName: 'Inbox log', query: 'label:inbox newer_than:2d', maxThreads: 30 };

function logMessages() {
  var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(GL.sheetName);
  var last = sheet.getLastRow();
  var known = {};
  if (last > 1) {
    sheet.getRange(2, 4, last - 1, 1).getValues().forEach(function (r) { known[r[0]] = true; });
  }
  var rows = [];
  GmailApp.search(GL.query, 0, GL.maxThreads).forEach(function (thread) {
    thread.getMessages().forEach(function (m) {
      var id = m.getId();
      if (known[id]) return;
      known[id] = true;
      rows.push([m.getDate(), m.getFrom(), m.getSubject(), id]);
    });
  });
  if (rows.length) sheet.getRange(sheet.getLastRow() + 1, 1, rows.length, 4).setValues(rows);
  return rows.length;
}

What you should see

Each message is logged once. Sample values, not output from a real account.

Common errors and fixes

The same message is logged again

Column D must keep the message ID. Do not delete it.

Nothing is logged

Test the search text in Gmail first. newer_than limits the window.

Exceeded maximum execution time

Lower maxThreads and run more often.

Permissions. Running this script asks you to grant Google permissions for the services listed above, to your own script. TriggerShelf never receives your Google data. See the permissions table. Google will show "Google hasn't verified this app"; that is expected for a script you paste yourself.

TriggerShelf is independent and not affiliated with or endorsed by Google LLC. Google Sheets, Gmail, Google Drive and Apps Script are trademarks of Google LLC. Quota figures come from Google's Apps Script quotas page. Test on a copy first.