# Mailcheck AI integration on Definable

> Mailcheck is an email verification service that helps businesses validate email addresses to ensure deliverability and reduce bounce rates.

## What this connects

Mailcheck is an email verification service that helps businesses validate email addresses to ensure deliverability and reduce bounce rates.

Vendor: https://www.usercheck.com/

## Tools available

**2** tools available. First 2:

- `MAILCHECK_VALIDATE_DOMAIN` — Validate Domain — Tool to validate a domain for disposability, MX records, domain age, and spam indicators. Use when checking if a domain is associated with temporary email services, public email providers, or forwarding services.
- `MAILCHECK_VERIFY_EMAIL` — Verify Email Address — Tool to verify provided email address. Use after obtaining user email input.

## Auth

Auth schemes: `API_KEY`.

## How agents use Mailcheck

Inside a Definable workflow, Mailcheck is one of the tools the **Distributor specialist** can call. Example coordination patterns:

- **Researcher → Mailcheck** — the Researcher (GPT-5.5) pulls context from Mailcheck (records, threads, documents), synthesises findings, and briefs the rest of the team.
- **Writer → Distributor → Mailcheck** — the Writer (Claude Opus 4.7) drafts copy in brand voice, the Verifier passes it, then the Distributor writes the result into Mailcheck (create record, post message, draft email).
- **Designer / Engineer → Distributor → Mailcheck** — the Designer ships an asset or the Engineer ships a code change, the Distributor delivers it via Mailcheck (attach file, open PR comment, post status).

The Verifier checks every Mailcheck call. On rate limit, schema drift, or auth refresh it self-heals and retries — the workflow completes without manual intervention.

## Categories

- email — https://definable.ai/apps/category/email/
- developer tools — https://definable.ai/apps/category/developer-tools/

## Related

- HTML page: https://definable.ai/apps/mailcheck/
- Same category (email): https://definable.ai/apps/category/email/
- All integrations: https://definable.ai/apps/
- Workflow (multi-agent loop): https://definable.ai/workflow/
- Apps llms.txt index: https://definable.ai/llms-apps.txt