# How to use ChatGPT to verify an email list with looot

Check which addresses will accept mail before you send, one call per address, with the reason for each verdict.

## Connect looot to ChatGPT

1. Open ChatGPT Plugins at chatgpt.com/plugins.
2. Select the plus button, then "Add custom MCP server".
3. Enter a name (looot) and a short description, for example: live data APIs, paid per call.
4. Under Connection, choose Public endpoint and paste https://api.looot.ai/mcp, including the /mcp path.
5. Configure authentication, read the risk warning and select "I understand and want to continue".
6. Select "Create as a plugin", review the tools ChatGPT found on the server, then install the plugin.
7. looot's sign-in page opens when ChatGPT first needs your account: sign in and allow access. Runs are paid from your prepaid looot balance.

OpenAI's guide does not say which ChatGPT plans can add a custom MCP server. It says account and workspace policies apply to adding and using custom MCP servers.

- Source, read 2026-11-10: [OpenAI developer docs: Connect and test your plugin](https://developers.openai.com/apps-sdk/deploy/connect-chatgpt)

## Ask ChatGPT

Start a new conversation, type @ in the prompt box and select the looot plugin. Then paste the prompt.

Use looot to check each email address below with the job people.email.verify, one call per address. Return a table with the address, the status and the reason the provider gave. Mark catch-all domains separately, because no provider can prove a single mailbox exists on them.

[One email address per line]

## Jobs it calls and what they cost

One use costs from $0.00025 at today's cheapest providers. A provider that misses can fall back to the next one, which can cost more; looot charges only the calls that ran, from your prepaid balance.

- `people.email.verify`: 1 call, from $0.00025 per call (Filtrat, the cheapest of 13 providers). Compare providers: [people.email.verify benchmark](/benchmarks/people-email-verify). [About the cheapest provider](/providers/filtrat)

## A real run

We ran this task through the looot MCP on 2026-11-10. Asked: p****@stripe.com, the address the work email guide found. Total charged: $0.

- people.email.verify on filtrat-verify-email (Filtrat): answered, rated weak, charged $0. Run id run_716a2c5bc35a4884ba49555682055e2e.
- Status: verified, confidence 98 out of 100. Not disposable, not a role address, syntax valid.
- The domain is catch-all and its mail runs on Google Workspace, so the mailbox itself cannot be proven.
- looot rated the answer weak and charged $0 for it.

## Good to know

- A catch-all domain accepts mail for any address, so a verifier can only say the domain works. looot counts that answer as weak, not as a hit.

## More

- [The same task in Claude](/guides/claude/verify-email-list)
- [The prompt on its own](/prompts/verify-email-list)
- [All ChatGPT guides](/guides/chatgpt)