Rate Limits

{
  "status": "error",
  "error_code": "rate_limit_exceeded",
  "message": "Too many requests. Please retry after 60 seconds.",
  "retry_after": 60
}

async function sendWithBackoff(url, payload, maxRetries = 5) {
  for (let attempt = 0; attempt < maxRetries; attempt++) {
    const response = await fetch(url, {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
        "Authorization": "Bearer YOUR_API_KEY",
      },
      body: JSON.stringify(payload),
    });

    if (response.status === 429) {
      const body = await response.json();
      const retryAfter = body.retry_after || 60;
      const backoff = retryAfter * 1000 * Math.pow(2, attempt);

      console.log(`Rate limited. Retrying in ${backoff / 1000}s (attempt ${attempt + 1})`);
      await new Promise((resolve) => setTimeout(resolve, backoff));
      continue;
    }

    return await response.json();
  }

  throw new Error("Max retries exceeded");
}

# Send a request and check for 429 status
curl -s -w "\nHTTP Status: %{http_code}\n" \
  -X POST https://app.lettr.com/api/emails \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "from": "you@example.com",
    "to": ["recipient@example.com"],
    "subject": "Hello",
    "html": "<p>Hi there</p>"
  }'

function chunkRecipients(recipients, size = 50) {
  const chunks = [];
  for (let i = 0; i < recipients.length; i += size) {
    chunks.push(recipients.slice(i, i + size));
  }
  return chunks;
}

async function sendToAll(recipients, emailPayload) {
  const chunks = chunkRecipients(recipients);

  for (const chunk of chunks) {
    await sendWithBackoff("https://app.lettr.com/api/emails", {
      ...emailPayload,
      to: chunk,
    });

    // Pause between requests to avoid hitting rate limits
    await new Promise((resolve) => setTimeout(resolve, 1000));
  }
}

async function processQueue(queue, emailPayload, delayMs = 1000) {
  const chunks = chunkRecipients(queue, 50);
  let sent = 0;

  for (const chunk of chunks) {
    try {
      await sendWithBackoff("https://app.lettr.com/api/emails", {
        ...emailPayload,
        to: chunk,
      });
      sent += chunk.length;
      console.log(`Sent ${sent} / ${queue.length}`);
    } catch (error) {
      console.error(`Failed at ${sent} sent. Error: ${error.message}`);
      // Re-queue remaining recipients
      const remaining = queue.slice(sent);
      console.log(`Re-queuing ${remaining.length} recipients for retry.`);
      return processQueue(remaining, emailPayload, delayMs);
    }

    await new Promise((resolve) => setTimeout(resolve, delayMs));
  }

  console.log(`All ${queue.length} recipients processed.`);
}