ChatGPT guide

Verify an email list with ChatGPT

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

1. Connect looot to ChatGPT

Open ChatGPT Plugins at chatgpt.com/plugins.
Select the plus button, then "Add custom MCP server".
Enter a name (looot) and a short description, for example: live data APIs, paid per call.
Under Connection, choose Public endpoint and paste https://api.looot.ai/mcp, including the /mcp path.
Configure authentication, read the risk warning and select "I understand and want to continue".
Select "Create as a plugin", review the tools ChatGPT found on the server, then install the plugin.
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

2. Ask ChatGPT

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

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]

3. Jobs it calls and what they cost

people.email.verify
1 call, from $0.00025 per call (Filtrat, the cheapest of 13 providers)
Compare providers About the cheapest provider

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.

Providers in the real run below:Filtrat

4. 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.

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.

people.email.verify on filtrat-verify-email (Filtrat): answered, rated weak, charged $0. Run id run_716a2c5bc35a4884ba49555682055e2e.

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.

The same task in Claude The prompt on its own All ChatGPT guides

Give your agent every data provider, one key.

Start your workspace, top up, and paste one prompt into the agent you already use.

Start your workspace See what agents can do