# Mails.so AI integration on Definable

> Mails is an API service that provides powerful email validation capabilities to help maintain a clean and effective email list.

## What this connects

Mails is an API service that provides powerful email validation capabilities to help maintain a clean and effective email list.

Vendor: https://mails.so

## Tools available

**3** tools available. First 3:

- `MAILS_SO_RETRIEVE_BATCH_RESULTS` — Retrieve Batch Results — Tool to retrieve results of a bulk validation job. Use after submitting a batch and you have its ID.
- `MAILS_SO_VALIDATE_BULK_EMAILS` — Validate Bulk Emails — Tool to validate multiple email addresses in bulk. Use when you need to confirm deliverability of a list of emails at once.
- `MAILS_SO_VALIDATE_SINGLE_EMAIL` — Validate Single Email — Tool to validate a single email address. Use when you need to check deliverability and quality details before sending an email.

## Auth

Auth schemes: `API_KEY`.

## How agents use Mails.so

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

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

The Verifier checks every Mails.so 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/mails_so/
- 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