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Verify a column of email addresses right inside Google Sheets with a short Apps Script: no add-on, no server, no install. Use the =MT_VERIFY(A2) formula in any cell, or verify a whole column in one run. MailTester Ninja checks each address against the recipient’s mail server.
What you need
- A Google account and a spreadsheet with your addresses in column A.
- A key: a free API token to try it (50 checks a day, one request every 30 seconds) or a paid key for full speed. Use a token rather than
key=free: the keyless tier is counted per IP, and Google shares its IP addresses between users.
Set it up in two minutes
- Open your sheet and go to Extensions, Apps Script.
- Paste the content of our Code.gs script.
- In Project Settings, Script Properties, add
MAILTESTER_KEYwith your token or key. - Save the project.
Use it
- One cell:
=MT_VERIFY(A2)returns the verdict (Accepted, Rejected, Catch-All…). Sheets caches custom function results: edit the cell to refresh it. - A whole column: run
verifyColumn()from the editor. It reads column A from row 2, writes the code in column B and the message in column C, and paces itself to respect the rate limit.
| code | Meaning | What to do |
|---|---|---|
ok | Valid and deliverable | Keep the address. |
ko | Invalid, will bounce | Remove it from your list. |
mb | Uncertain (catch-all domain, server could not be probed) | Review it, or decide by risk. |
-- | No verdict (key problem, or free limit reached with HTTP 429) | Run it again later. Never delete the address on this answer. |
How fast
With a free token, verifyColumn() waits 30 seconds between rows, and an Apps Script run stops after 6 minutes: about 11 rows per run. A paid key goes 30 times faster.
Questions
Is there a MailTester Ninja add-on for Google Sheets?
Not yet. The script does the same job today, and this page will announce an add-on when it is published.
Is anything stored?
No. Each address is checked in real time and we keep no copy of the addresses you verify.
Try it now
Get a free API token, or see the plans for up to 200,000 checks a day. Full reference: API documentation and OpenAPI specification. Back to all integrations.