---
title: SNDR
description: Send transactional email through the SNDR HTTP API with createMailer.
icon: Truck
source: "src/transports/sndr.ts"
---

Use SNDR for app-triggered email — receipts, sign-in mail, and other transactional sends — over HTTPS JSON.
Wire `SndrTransport` into `createMailer`; do not call `@rkiza/sndr` from application code.

<LiveVerified>
Email send against SNDR’s production API succeeded in sently’s opt-in live suite (verified domain + real recipient).
</LiveVerified>

<Callout title="The one rule">
  Import from `sently/transports/sndr`, pass the transport to `await createMailer(...)`, and send
  with the mailer — keep delivery on the email channel.
</Callout>

## Quick start

<Steps>

<Step>
### Configure

```ts
import { createMailer } from "sently/mailer";
import { SndrTransport } from "sently/transports/sndr";

const mailer = await createMailer({
  transport: new SndrTransport({
    apiKey: process.env.SNDR_API_KEY!,
  }),
});
```

</Step>

<Step>
### Send

```ts
const result = await mailer.send({
  from: "hello@yourdomain.com",
  to: "customer@example.com",
  subject: "Welcome aboard",
  html: "<p>Thanks for joining us.</p>",
});
```

</Step>

<Step>
### See the result

```ts
console.log(result.messageId); // e.g. em_…
console.log(result.response); // e.g. queued
```

`from` must use a domain verified in the [SNDR dashboard](https://www.sndr.sh/) (SPF, DKIM, DMARC).

</Step>

</Steps>

## Configuration

| Option | Type | Default | Meaning |
| ------ | ---- | ------- | ------- |
| `apiKey` | `string` | required | Bearer key (`sndr_live_…` / `sndr_test_…`). |
| `baseUrl` | `string` | `https://api.sndr.sh` | API origin (no trailing slash needed). |
| `defaultTemplateId` | `string` | — | Default SNDR `template_id` when not set per message. |

## Message mapping

| Mail option | SNDR field | Notes |
| ----------- | ---------- | ----- |
| `from` | `from` | MIME form `Name <addr>` when a display name is present. |
| `to` / `cc` / `bcc` | `to` / `cc` / `bcc` | Arrays of email addresses. |
| `replyTo` | `reply_to` | First address only. |
| `subject` | `subject` | Required. |
| `html` / `text` | `html` / `text` | Optional body fields. |
| `headers` | `headers` | Custom headers; template header is stripped. |
| `idempotencyKey` / `messageId` | `Idempotency-Key` | Sent when present. |
| `data` | `variables` | Only when a template id is set. |

`POST /v1/send` is idempotent when `Idempotency-Key` is supplied.

## Templates

Set a template with the `x-sndr-template-id` header (or `defaultTemplateId` on the transport).
Pass template variables through `data` (`{{ variable }}` placeholders on SNDR).

```ts
import { SNDR_TEMPLATE_ID_HEADER } from "sently/transports/sndr";

await mailer.send({
  from: "hello@yourdomain.com",
  to: "customer@example.com",
  subject: "Welcome",
  headers: { [SNDR_TEMPLATE_ID_HEADER]: "tpl_welcome" },
  data: { name: "Ada" },
});
```

## Verify and errors

`verify()` calls `GET /v1/domains` with the same Bearer key.

Failed HTTP responses throw `SndrError` (`SentlyError`) with the API `error.message` when present.

| SNDR `error.code` (common) | Meaning |
| --- | --- |
| `invalid_request` | Malformed payload |
| `unauthenticated` | Missing or invalid API key |
| `rate_limited` | Slow down |
| `domain_not_verified` | Verify the sending domain first |
| `recipient_suppressed` | Address is on the suppression list |

## Webhooks

Import from `sently/webhooks/sndr`. Verify `X-Sndr-Signature` (`t=…,v1=…`) over the **raw** body, then `parse`.

| SNDR event | Normalized `EmailEvent.type` |
| --- | --- |
| `email.queued` | `deferred` |
| `email.delivered` | `delivered` |
| `email.bounced` | `bounced` |
| `email.failed` | `unknown` |
| `email.complained` | `complained` |
| `email.opened` | `opened` |
| `email.clicked` | `clicked` |
| `email.unsubscribed` | `unknown` |

See [Webhooks](/docs/guides/webhooks#sndr-signatures) for the HMAC details.

## What sently covers vs SNDR platform

| Surface | In sently | Notes |
| --- | --- | --- |
| Send (`POST /v1/send`) | Yes — `SndrTransport` | Channel: `createMailer` |
| Templates + variables | Yes | Header / `defaultTemplateId` + `data` |
| Idempotency | Yes | `idempotencyKey` / `messageId` |
| Domain verify | Yes — `verify()` | `GET /v1/domains` |
| Delivery webhooks | Yes — `sently/webhooks/sndr` | Signed parse |
| Contacts / contact groups / broadcasts | No | SNDR dashboard / their API |
| Analytics / suppressions admin | No | Use SNDR dashboard |
| Attachments on HTTP send | Not mapped | Prefer SMTP or ask SNDR if their send API gains attachments |

## Troubleshooting

<Accordions>

<Accordion title="from domain is not verified">

SNDR rejects sends from unverified domains. Add SPF, DKIM, and DMARC in the dashboard Domains page, click Verify, then retry with that domain in `from`.

</Accordion>

<Accordion title="recipient_suppressed">

The address is on SNDR’s suppression list (bounce/complaint). Remove it only if the recipient opted back in; otherwise pick another address.

</Accordion>

<Accordion title="Should I import SndrTransport from sently?">

No. Use `sently/transports/sndr`. The main `sently` package does not re-export HTTP provider transports.

</Accordion>

<Accordion title="Should I call the @rkiza/sndr SDK?">

No. Use `createMailer` plus `SndrTransport`. Keep vendor extras off the shared email contract.

</Accordion>

</Accordions>

## Contact & resources

| Contact | Detail |
| --- | --- |
| Direct email | [sndr@rkiza.sa](mailto:sndr@rkiza.sa) |
| Contact form | [sndr.sh/contact](https://www.sndr.sh/contact) |
| Docs | [sndr.sh/docs](https://www.sndr.sh/docs) |
| API reference | [API Reference](https://www.sndr.sh/docs/api-reference) |
| Status | [sndr.sh/status](https://www.sndr.sh/status) |
| X / Twitter | [@usesndr](https://x.com/usesndr) |
| LinkedIn | [SNDR company](https://www.linkedin.com/company/104143949) |
| GitHub | [github.com/rkiza/sndr](https://github.com/rkiza/sndr) |

## Learn more

- [Email channel](/docs/channels/email) — mailer options and send pipeline
- [Webhooks](/docs/guides/webhooks) — SNDR delivery events and signature verification
- [Bundle size](/docs/guides/bundle-size) — why subpath imports stay small

## Next

<Cards>
  <Card title="Email channel" description="createMailer and MailOptions." href="/docs/channels/email" />
  <Card title="Webhooks" description="Parse and verify SNDR events." href="/docs/guides/webhooks" />
  <Card title="Transports" description="All provider transports by channel." href="/docs/transports" />
</Cards>