API‑First Email: How Developers Use Our Platform

For engineering‑led teams, an API‑first approach unlocks possibilities that no drag‑and‑drop interface can match.

API architecture

RESTful with JSON. Bearer‑token auth. 1,000 requests/minute for Pro, custom limits for Enterprise. Pagination and rate‑limit headers in every response.

Authentication

Public keys (client‑side, restricted) and private keys (server‑side, full access). Rotate quarterly, store in environment variables.

Sending the first email

Use `/v1/campaigns/send` with recipients, subject, template ID, and dynamic data. Delivery in about 30 seconds. Check status at `/v1/messages/{id}`.

Webhook integration

Events: `email.sent`, `delivered`, `opened`, `clicked`, `bounced`, `complained`, `subscriber.unsubscribed`. Always validate HMAC signatures.

Batch operations

Use `/v1/campaigns/batch` for up to 10,000 recipients per request. For larger lists: chunked uploads or streaming API.

Error handling

Exponential backoff on 429 and 5xx. Maximum 3 retries (1s, 4s, 16s). ACK webhook events within 5s; move heavy processing to background queues.

SDKs

Official Node.js, Python, Ruby, Go, and PHP SDKs. Community‑maintained Rust, Java, and .NET. All open source.

Best practices

1. Use idempotency keys. 2. Implement circuit breakers. 3. Monitor `/v1/analytics` closely. 4. Use sandbox mode (`test_` prefixes). 5. Alert on bounce rates >5%. 6. Log all interactions.