Integrating the SprintMailer Email API: A Developer's Guide

SprintMailer provides a RESTful email API designed for developers who need reliable transactional delivery, template management, and real-time event tracking. This guide covers everything from authentication to production deployment.

Prerequisites

• SprintMailer account with API access enabled
• Verified sending domain (SPF, DKIM, DMARC configured)
• API key from your dashboard

Authentication

All API requests require a Bearer token:

Authorization: Bearer YOUR_API_KEY

Store keys in environment variables—never commit them to source control. Rotate keys periodically and use separate keys for staging and production.

Send Your First Email

curl -X POST https://api.sprintmailer.com/v1/emails \
  -H "Authorization: Bearer $SPRINTMAILER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "from": "SprintMailer <[email protected]>",
    "to": "[email protected]",
    "subject": "Hello from SprintMailer",
    "html": "<p>Your integration works!</p>"
  }'

Successful responses include a message ID for tracking and webhook correlation.

Use Templates Instead of Inline HTML

For production applications, store templates in SprintMailer:

{
  "to": "[email protected]",
  "template": "welcome",
  "variables": {
    "name": "Alex",
    "login_url": "https://app.com/login"
  }
}

Benefits: update copy without deploys, version control, preview with test data, consistent branding via Brand Kit.

Webhook Events

Configure webhook endpoints to receive:

| Event | Use Case | |-------|----------| | delivered | Confirm successful delivery | | bounced | Suppress invalid addresses | | complained | Remove from all lists immediately | | opened | Engagement tracking (optional) | | clicked | Conversion attribution |

Verify webhook signatures to prevent spoofed events. Respond with HTTP 200 within 5 seconds; process asynchronously for heavy logic.

Error Handling

Common API errors and responses:

• 401 — Invalid or missing API key
• 422 — Validation error (check errors array)
• 429 — Rate limit exceeded; implement exponential backoff
• 500 — Transient server error; retry with backoff

async function sendWithRetry(payload, maxRetries = 3) {
  for (let attempt = 0; attempt < maxRetries; attempt++) {
    const res = await fetch("https://api.sprintmailer.com/v1/emails", {
      method: "POST",
      headers: {
        Authorization: `Bearer ${process.env.SPRINTMAILER_API_KEY}`,
        "Content-Type": "application/json",
      },
      body: JSON.stringify(payload),
    });
    if (res.ok) return res.json();
    if (res.status === 429 || res.status >= 500) {
      await new Promise((r) => setTimeout(r, 2 ** attempt * 1000));
      continue;
    }
    throw new Error(await res.text());
  }
}

Sandbox Mode

Enable sandbox in your dashboard for development. Sandbox captures all outgoing messages without delivery—inspect rendered HTML, test variables, and debug integrations safely.

Never use production API keys in CI test suites. Use sandbox keys with mocked webhook endpoints.

SDKs and Language Support

SprintMailer provides SDKs for:

• Node.js / TypeScript
• Python
• PHP
• Ruby
• Go
• .NET

Each SDK wraps authentication, retry logic, and typed responses. Raw HTTP works equally well for other languages.

SMTP Alternative

Prefer SMTP? Use the same API key as SMTP password:

Host: smtp.sprintmailer.com
Port: 587 (STARTTLS)
User: apikey
Pass: YOUR_API_KEY

Both API and SMTP share logging, authentication, and deliverability infrastructure.

Production Checklist

• [ ] Sending domain authenticated (SPF, DKIM, DMARC)
• [ ] Templates created and previewed
• [ ] Webhooks configured with signature verification
• [ ] Suppression logic connected to bounce/complaint events
• [ ] Rate limiting and retry logic implemented
• [ ] Sandbox tested; production keys secured
• [ ] Monitoring alerts set for delivery rate drops

Conclusion

SprintMailer API integration typically takes under 30 minutes for basic sending and a few hours for full webhook-driven production setup. Reliable email infrastructure should be boring—that is the goal.

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