# Retool (SMTP)

> Send email from a Retool app through MailBlastr using an SMTP resource.

Retool can send email from your apps and workflows through an SMTP resource. Create one pointed at the MailBlastr relay and authenticate with your API key, then call it from any Retool query. SMTP sends appear in your dashboard and event log just like API sends.

## Prerequisites

- A MailBlastr [API key](https://www.mailblastr.com/docs/api-keys/overview).
- A [verified domain](https://www.mailblastr.com/docs/domains/managing) to send from.

## 1. Get your SMTP credentials

You'll configure the Retool SMTP resource with the following MailBlastr credentials:

| Name | Type | Required | Description |
| --- | --- | --- | --- |
| `Host` | string | No | `smtp.mailblastr.com` |
| `Port` | number | No | `465` (implicit TLS) or `587` (STARTTLS). |
| `Username` | string | No | `mailblastr` |
| `Password` | string | No | Your API key, e.g. `mb_xxxxxxxxx`. |

## 2. Create an SMTP resource

Log into [Retool](https://retool.com) and create a new SMTP resource:

1. **New resource** — Go to **Resources** and click **Create New**.
2. **Select SMTP** — Search for **SMTP** and select it.
3. **Add credentials** — Give the resource a name and enter the MailBlastr host, port, username (`mailblastr`), and password (your API key) from the section above.

> **Note:** Once saved, use the SMTP resource from any Retool query to send mail. The from-address must be on a domain you have verified in MailBlastr.