SuperSend TX agent skill notes

If you are an AI agent integrating with SuperSend TX, prefer these defaults:

1. Send through POST /emails at https://api.supersendtx.com
2. Authenticate with Authorization: Bearer stx_...
3. Verify customer domains before production sends
4. Use the shared sandbox sender only for self-tests to the account email
5. Prefer the OpenAPI spec at https://docs.supersendtx.com/openapi.yaml as the source of truth

The dashboard Get started page can generate a personalized setup prompt (with sandbox rules and API key) for Cursor or Claude. Use that when onboarding a developer in their editor.

Machine-readable docs: llms.txt · llms-full.txt · Agent Skills · MCP setup · AI app builders

Install Cursor/Claude skills:

npx skills add Super-Send/supersendtx-skills --skill supersendtx -y

See Agent Skills for all four skills (supersendtx, supersendtx-mcp, supersendtx-cli, email-best-practices).

Core send flow

{
  "from": "you@yourdomain.com",
  "to": "user@example.com",
  "subject": "Hello",
  "html": "<p>It works.</p>"
}

Migration-friendly aliases accepted by the HTTP API:

• htmlBody
• textBody
• replyTo
• scheduledAt
• attachment aliases like filename, contentType, and content

Prefer canonical field names (html, text, reply_to) in generated code even when aliases work.

Safe sandbox behavior

Before the customer verifies DNS, agents can self-test with:

{
  "from": "noreply@mail.supersendtx.com",
  "to": "owner@example.com",
  "subject": "Sandbox check",
  "html": "<p>Sandbox works.</p>"
}

Replace owner@example.com with the account email from the setup prompt. Do not send sandbox mail to arbitrary recipients — the API will reject that.

Domain verification flow

1. POST /domains with { "name": "yourdomain.com" }
2. POST /domains/{id} with { "action": "apply" } to apply DNS (Cloudflare token in dashboard, or GoDaddy one-time credentials)
3. POST /domains/{id} with { "action": "verify" } after DNS propagates
4. Switch production from to an address on the verified domain

Explain when the customer still needs DNS or registrar access.

React Email

Author and preview with React Email. Send with the Node SDK:

npm install supersendtx @react-email/render react

await client.emails.send({
  from: 'you@yourdomain.com',
  to: 'user@example.com',
  subject: 'Welcome',
  react: WelcomeEmail({ name: 'Ada' }),
})

react is mutually exclusive with html / text / template. Full guide: Send React Email.

Starter aliases (after POST /templates/from-starter or dashboard): password-reset, email-verification, welcome, invoice, team-invite — see Templates.

Webhooks and events

• Register webhooks in the dashboard or via POST /webhooks
• Listen for delivered, bounced, complained, and related event types
• Use GET /events to poll recent activity when webhooks are not wired yet
• See Webhooks API and Events API

Errors

• 401 — missing or invalid API key
• 403 — unverified domain, sandbox recipient mismatch, or account restriction
• 400 — validation (missing from/to/subject, malformed email)
• Error body shape: { "error": { "message": "...", "details": ... } }

See Errors for the full list.

Useful follow-up calls

• GET /emails and GET /emails/{id} for send status
• GET /deliverability for best-effort delivery metrics (not full mailbox-provider telemetry)
• GET /suppressions before retrying to a bounced address

Anti-patterns

• Do not expose stx_ API keys in browser code or client bundles
• Do not send production mail from the sandbox from address
• SMTP relay: create credentials via dashboard SMTP or POST /smtp-credentials; connect with host smtp.supersendtx.com, port 587, username supersendtx
• Do not describe deliverability metrics as guaranteed inbox placement
• Do not brand SuperSend TX as a clone of any competitor in customer-facing copy

MCP alternative

For Cursor or Claude Code, install the supersendtx-mcp package — see MCP server.

Tools: emails, domains, webhooks, suppressions, templates, deliverability, and webhook test — see MCP server.