The endpoint

Open a sheet, go to Extensions > Apps Script, and paste:

const SECRET = 'change-me';

function doPost(e) {
  const p = e.parameter;
  if (p.token !== SECRET) {
    return json({ ok: false, error: 'bad token' });
  }
  const email = String(p.email || '').trim();
  if (!/^[^@\s]+@[^@\s]+\.[^@\s]+$/.test(email)) {
    return json({ ok: false, error: 'bad email' });
  }
  SpreadsheetApp.getActiveSheet()
    .appendRow([new Date(), String(p.name || ''), email, '', '']);
  return json({ ok: true });
}

function json(obj) {
  return ContentService.createTextOutput(JSON.stringify(obj))
    .setMimeType(ContentService.MimeType.JSON);
}

Then deploy it: Deploy > New deployment > type "Web app" > Execute as "Me" > Who has access "Anyone". Copy the URL ending in /exec.

The form

Any HTML form can post to it:

<form action="YOUR_EXEC_URL" method="POST">
  <input name="name" placeholder="Your name">
  <input name="email" type="email" required placeholder="you@company.com">
  <input type="hidden" name="token" value="change-me">
  <button type="submit">Send</button>
</form>

Each submission lands as a row: timestamp, name, email, plus two empty columns (status, sent_at) that an auto-reply script can use later.

Honest caveats

• The token in a public page is visible in the source. It stops drive-by bots, not a determined human. For anything sensitive, add real spam protection (a honeypot field helps too).
• "Anyone" access means anyone with the URL can post. That is the point of a lead form, but do not reuse the same script for private data.
• Apps Script caps concurrent executions and daily runtime. For ordinary lead volumes you will never notice; for a launch-day spike, test first.

Where this goes next

Once leads land in the sheet, the auto-reply script from my earlier post answers them within minutes, and the follow-up script bumps the quiet ones after 48 hours.

All three pieces - the webhook, the auto-reply, and the follow-up - are packaged with editable email templates and a 10-minute setup guide in the LeadReply Kit. The kit is mock-tested sample code, so read it before pointing it at real leads.

Here is a small Google Apps Script that does exactly that from the same Google Sheet you use to track leads. It pairs with the auto-reply script from my earlier post, but it also works on its own.

The sheet layout

Same columns as before: email, status, sent_at. The first script sets status to sent and stamps sent_at when it replies. This one looks for rows that are still sent (never replied to) with a sent_at older than 48 hours.

How it knows the lead never replied

It asks Gmail. If any message from the lead's address arrived after your first reply went out, the lead is not quiet, so the script skips them:

function sendFollowUps() {
  const sheet = SpreadsheetApp.getActiveSheet();
  const rows = sheet.getDataRange().getValues();
  const head = rows[0];
  const col = n => head.indexOf(n);
  const HOURS = 48;
  const MAX_PER_RUN = 10;
  const now = Date.now();
  let sent = 0;

  for (let i = 1; i < rows.length && sent < MAX_PER_RUN; i++) {
    if (String(rows[i][col('status')]) !== 'sent') continue;
    const sentAt = new Date(rows[i][col('sent_at')]);
    if (isNaN(sentAt) || (now - sentAt) < HOURS * 3600 * 1000) continue;

    const email = String(rows[i][col('email')]).trim();
    const replied = GmailApp.search(`from:${email} after:${Math.floor(sentAt.getTime() / 1000)}`, 0, 1);
    if (replied.length > 0) {
      sheet.getRange(i + 1, col('status') + 1).setValue('replied');
      continue;
    }

    GmailApp.sendEmail(email, 'Still happy to help', 'Hi, just bumping this in case it got buried. Happy to answer any questions - or if now is not the right time, no worries at all.');
    sheet.getRange(i + 1, col('status') + 1).setValue('followed_up');
    sent++;
  }
}

What it does, line by line

• Only touches rows marked sent with a sent_at at least 48 hours old.
• Searches Gmail for anything from the lead after your first reply. A reply flips the row to replied so you never follow up with someone who already wrote back.
• Sends one short follow-up, then marks the row followed_up so it never sends a second one.
• MAX_PER_RUN caps each run. Schedule it with a time-driven trigger (Triggers > Add trigger > hourly) and it stays far under Gmail's daily sending limits.

Two things that matter more than the code

Keep the follow-up short and human. Two sentences, no pitch, no "just checking in" three times over. And stop after one. A lead who ignores two emails was never going to buy from the third.

I packaged this follow-up, the instant auto-reply, editable email templates, and a 10-minute setup guide into the LeadReply Kit if you would rather skip the wiring. The kit is mock-tested sample code, so read it before pointing it at real leads.

Sheet layout

Row 1 headers: name, email, status, sent_at. New leads are rows with an empty status.

The script

Open Extensions > Apps Script and paste:

function replyToNewLeads() {
  const sheet = SpreadsheetApp.getActiveSheet();
  const rows = sheet.getDataRange().getValues();
  const head = rows[0];
  const col = n => head.indexOf(n);
  const MAX_PER_RUN = 20;
  let sent = 0;
  for (let i = 1; i < rows.length && sent < MAX_PER_RUN; i++) {
    const email = String(rows[i][col('email')]).trim();
    if (rows[i][col('status')]) continue;
    if (!/^[^@\s]+@[^@\s]+\.[^@\s]+$/.test(email)) {
      sheet.getRange(i + 1, col('status') + 1).setValue('invalid');
      continue;
    }
    GmailApp.sendEmail(email, 'Thanks for reaching out',
      'Hi ' + rows[i][col('name')] + ',\n\nThanks for your message. We will be in touch shortly.\n');
    sheet.getRange(i + 1, col('status') + 1).setValue('sent_1');
    sheet.getRange(i + 1, col('sent_at') + 1).setValue(new Date());
    sent++;
  }
}

Run it on a timer

In Apps Script, open Triggers (the clock icon), add a trigger for replyToNewLeads, time-driven, every 5 minutes.

Things to know

• Free Gmail allows about 100 scripted recipients a day, Google Workspace about 1,500.
• Only email people who asked to hear from you.
• The status column stops duplicates. Do not clear it unless you want a resend.

Want the polished version?

I packaged this with HTML email templates, a timed follow-up for people who do not reply, a duplicate lock and a setup guide as LeadReply Kit ($29). The script above works fine on its own, though.