💡 New script: sheets-mail-merge (personalized bulk emails from Sheets data)

[github-actions[bot]]

Summary

A Google Apps Script that reads rows from a Google Sheet where each row represents a recipient, merges row data into a configurable email template using {{placeholder}} syntax, and sends personalized emails via MailApp. Supports plain text and HTML templates, draft preview before sending, and a send-log column that prevents duplicate sends on re-runs. Configurable via the browser-based deploy page.

Market Signal

Mail merge is an evergreen top-3 GAS automation request. Yet Another Mail Merge (YAMM) has 10M+ installs on the Google Workspace Marketplace at $25/year. Mailmeteor, GMass, and Mail Merge with Attachments collectively serve millions more users — all paid. No free, open-source, browser-deployable mail merge exists. The relaxed MailApp quotas in 2026 (UrlFetch daily data-received cap removed, increased size limits) make this more viable at scale. Apps Script's promotion to a Google Workspace Core Service (June 2026) validates the platform for production automation.

User Signal

"Google Sheets mail merge script" is consistently one of the top GAS-related search queries. Community research identifies mail merge and document generation as top-requested automation workflows. The project's target persona — non-technical users who want to automate without code — is exactly the audience currently paying $25/year for YAMM or $30/month for Zapier mail merge workflows.

Technical Opportunity

MailApp and SpreadsheetApp are core GAS services. The {{placeholder}} template pattern is simple to implement and test. The send-log column (marking rows as "sent" with timestamp) provides idempotency — the same deduplication pattern used by gmail-to-drive-by-labels for thread dedup. Config schema: sheet ID, template subject, template body, recipient column, status column. The SCRIPT_CATALOG entry with Sheets picker integration is already proven in calendar-to-sheets.

Assessment

Dimension	Score	Rationale
Feasibility	high	MailApp and SpreadsheetApp are core services. Template rendering is straightforward string replacement. Send-log pattern is proven.
Impact	high	Displaces $25/year paid tools with 10M+ combined installs. Mail merge is one of the most commercially validated GAS use cases.
Urgency	med	Demand is steady and evergreen. Not tied to a specific market event, but the commercial market has matured without an open-source contender.

Adversarial Review

Strongest objection: MailApp has a daily email quota (100 for free accounts, 1500 for Workspace). Users will hit limits on large lists and blame the tool.

Rebuttal: The quota is a GAS platform constraint, not a design flaw. Mitigation: (1) configurable batch size with clear quota documentation in the UI, (2) send-log column ensures interrupted batches resume correctly on next trigger run — no duplicates, (3) daily quota check before send loop with user-friendly "quota exhausted, will resume tomorrow" message, (4) draft-preview mode lets users verify merge output before sending. For the target persona (individuals, small teams), 100–1500 emails/day covers the vast majority of use cases: team updates, client outreach, event invitations, and newsletter sends.

Suggested Next Step

Create a tech spec defining the template syntax ({{column_name}} placeholders), config.gs schema, the send-log idempotency pattern, and the draft-preview mode that generates a sample email without sending. MVP scope: single template → per-row email send with status tracking. Phase 2: HTML templates, CC/BCC support, file attachment from Drive.