Global unsubscribe suppression for spreadsheet-based email tools

What to build

A lightweight unsubscribe-guard add-on for Google Sheets / Airtable / Zapier email senders that scans every row across all sheets and tabs for any address ever marked unsubscribed and blocks future sends to it, even when a new signup form re-adds that address as a fresh row.

No-code email stacks store unsubscribe status per row instead of per email address, so a new signup row silently resurrects an opted-out contact and exposes the sender to compliance complaints.

Demand

Solo marketers and indie makers running newsletters off spreadsheets hit this the moment a form re-adds a contact who already unsubscribed, and they have no built-in way to catch it before the next send.

• r/nocodeAnecdote

  Reddit thread: a person unsubscribed in July, a signup form added them back as a new row in August, and the sender tool mailed them again, prompting the question of how to stop opt-out from being a per-row property.

• Signal reporter (first-person account)Anecdote

  First-person account confirming unsubscribe status was stored per-row rather than per-address, causing a re-send after a new signup row was created.

Stack

• Google Sheets API
• Airtable API
• Zapier webhooks
• Supabase (suppression list storage)
• SendGrid/Postmark suppression API
• Node.js cron for periodic rescans

Solo + AI difficulty

Easy MVP in a few days: a scheduled script that dedupes by normalized email across sheets/tabs and cross-checks a global suppression table before any send. The hard part is handling multiple sheet schemas and Zapier's trigger timing reliably.

Entry threshold

Buildable by a solo developer in days: a script or small SaaS that connects to Google Sheets/Airtable API, maintains a global suppression list keyed by normalized email, and exposes a webhook or scheduled check other no-code tools can call before sending.

Window

ongoing

Where to find first users

• r/nocode
• r/Airtable
• Indie Hackers
• Zapier app marketplace listing
• Product Hunt launch

Counter-signals & risks

• Mainstream ESPs like Mailchimp, Klaviyo, and ConvertKit already enforce global suppression lists, so the gap is limited to pure spreadsheet/no-code stacks rather than the broader email marketing market.

• Airtable, Google Sheets, or Zapier could ship native deduplication/suppression features themselves, shrinking the need for a standalone add-on.

• The target buyers running compliance-sensitive campaigns off raw spreadsheets may be too small or too price-sensitive to sustain a dedicated paid product.