A mail merge is the one spreadsheet job where a mistake is sent to hundreds of people and can't be recalled. Mail Merge Pre-flight Check reads your recipient list in Google Sheets™ and your email template, finds what would go wrong, and shows you exactly what each recipient will receive — before anything sends.

WHAT IT CHECKS
- Broken fields: tags with no matching column, near-miss headers and syntax errors — including the "Dear {{First Name}}" email.
- Blank names: the recipients who would get "Hi ," — with the fallback syntax for your tool.
- Bad addresses: invalid syntax, duplicates, domain typos (jo@gmial.com), role and test addresses, and overlaps with your unsubscribe list.
- Wrong details, wrong person: a sorted column pairing one person's data with another person's address.
- Sending behaviour: filtered rows, already-sent rows, the list on the wrong tab for Gmail™ mail merge, and lists bigger than today's sending quota.

PREVIEW
The first 5 recipients plus the 3 worst rows, free. Pro steps through every recipient and writes a Preview tab.

READY TO SEND (PRO)
A clean tab for whichever merge tool you already use — YAMM™, Mailmeteor™, GMass™, Gmail™ mail merge, or any {{ }} / << >> merge — with fixes applied, duplicates and unsubscribed rows moved to an Excluded tab with reasons, batches by quota, and a Pre-flight report to keep with the send.

It never sends email and never changes your source tab. It sits in front of your merge tool, not in place of it, and only adds new tabs; "Remove pre-flight tabs" (free) deletes them again.

Free: unlimited checks with every finding and explanation, click-to-cell, the readiness badge, the preview of 5 + the 3 worst, and Remove pre-flight tabs. Pro (£4/month or £29/year): Ready to send and Excluded tabs, preview every recipient, batches by quota, report tab and CSV, saved campaigns with Re-check last list, mail-server lookup, 3 activations, 30-day full refund. Education and charities: 50% off.

YOUR DATA
No list or template content leaves Google. The add-on can reach only the spreadsheet it is opened in. The only things it sends anywhere are a licence key and an anonymous install id — plus domain names, and only if you switch the mail-server check on.

Google, Gmail™, Google Sheets™ and Google Workspace™ are trademarks of Google LLC. YAMM, Mailmeteor and GMass are trademarks of their respective owners. Mail Merge Pre-flight Check is not affiliated with or endorsed by Google, YAMM, Mailmeteor or GMass.