# Cold email for AI agents and developers | GTM and Outreach

Source: https://exntra.in/guides/cold-email-api

[All guides](/guides)

# Cold email for AI agents and developers

How to let a script or an AI assistant run cold email safely: API keys, MCP, idempotency, limits and confirmation.

Updated 2 November 2026, 5 minute read

Scripts and AI assistants can now run cold email end to end. That's powerful, and risky without guard rails. Here is how to set it up safely.

## Pick the right way in

-   **REST API** for your own code and tools like n8n or Make. JSON in, JSON out. [Quick start](/api/quickstart).
-   **MCP server** for AI assistants such as Claude and Cursor. The assistant gets 43 tools and asks before it sends. [Connect an assistant](/api/mcp).
-   **Webhooks** to react when someone replies, bounces or is labelled.

## Give each key only what it needs

Create a separate API key for each script or assistant. Choose a scope: full, campaigns, contacts, inbox, mailboxes, sending, or read-only. Limit it to one workspace if you can. Revoke it in one click when you're done.

## Never send twice

Networks fail and scripts retry. Send an `Idempotency-Key` header with every request that sends email. If the same request arrives again within 24 hours, you get the first result back instead of a second email.

## Respect the limits

-   300 requests a minute per key and 1,200 per account. Read the `X-RateLimit` headers, and wait for `Retry-After` on a 429.
-   Sending rules are the same as in the app: daily caps per mailbox, the slow start, bounce limits and the blocklist. Check them any time with `GET /v1/limits`.

## Keep a person in the loop

-   Let the assistant draft, import and check, then confirm before anything sends. Our MCP tools that send, launch or delete need `confirm: true`.
-   Use the pre-launch check and a test email, just as you would by hand.
-   Have replies go to the Master Inbox, where your team can see them.

## Give your assistant the docs

Point the assistant at `/llms.txt` on your API. It's the full reference as plain text, written for models to read.

## Start sending this week

Your first month is free and needs no card. Connect a mailbox, import a list and send your first test in about ten minutes.

[Start your free month](https://app.example.com/#/signup)[Talk to us](/contact)