Rate Limits | docs.do.dev

Send.dev implements rate limits to ensure fair usage and maintain service quality for all users. This page explains our rate limits and how to handle them.

Rate Limit Overview

Plan	Emails per Second	Emails per Day	API Requests per Minute
Free	1	100	60
Starter	10	10,000	300
Pro	50	100,000	1,000
Enterprise	Custom	Custom	Custom

Need Higher Limits?

Rate Limit Headers

Every API response includes headers showing your current rate limit status:

X-RateLimit-Limit: 300
X-RateLimit-Remaining: 299
X-RateLimit-Reset: 1705142460

Header	Description
`X-RateLimit-Limit`	Maximum requests allowed per window
`X-RateLimit-Remaining`	Requests remaining in current window
`X-RateLimit-Reset`	Unix timestamp when the window resets

Rate Limit Response

When you exceed the rate limit, the API returns a 429 Too Many Requests response:

{
  "error": {
    "code": "rate_limited",
    "message": "Rate limit exceeded. Please retry after 60 seconds.",
    "retry_after": 60
  }
}

The Retry-After header indicates how many seconds to wait before retrying.

Handling Rate Limits

Exponential Backoff

Implement exponential backoff when rate limited:

async function sendWithRetry(email: EmailRequest, maxRetries = 3) {
  for (let attempt = 0; attempt < maxRetries; attempt++) {
    try {
      return await send.emails.send(email);
    } catch (error) {
      if (error.code === 'rate_limited' && attempt < maxRetries - 1) {
        const delay = Math.pow(2, attempt) * 1000 + Math.random() * 1000;
        await sleep(delay);
        continue;
      }
      throw error;
    }
  }
}

Queue-Based Sending

For high-volume sending, implement a queue:

import { Queue } from 'your-queue-library';

const emailQueue = new Queue('emails', {
  rateLimiter: {
    max: 10,       // Max emails
    duration: 1000 // Per second
  }
});

emailQueue.process(async (job) => {
  await send.emails.send(job.data);
});

// Add emails to queue
await emailQueue.add({ to: 'user@example.com', ... });

Per-Endpoint Limits

Some endpoints have specific rate limits:

Endpoint	Limit	Notes
`POST /v1/emails`	Plan limit	Standard email sending
`POST /v1/emails/batch`	Plan limit / 10	Batch counts as multiple
`GET /v1/emails`	100/min	List/search operations
`POST /v1/domains/verify`	10/min	DNS verification

Best Practices

1. Use Batch Sending

Instead of many individual requests, use batch sending:

# Instead of 100 individual requests
curl -X POST /v1/emails -d '{"to": "user1@..."}'
curl -X POST /v1/emails -d '{"to": "user2@..."}'
# ... 98 more

# Use one batch request
curl -X POST /v1/emails/batch -d '{
  "emails": [
    {"to": "user1@...", ...},
    {"to": "user2@...", ...},
    // ... up to 100 emails
  ]
}'

2. Cache API Responses

Cache responses that don't change frequently:

// Cache domain list for 5 minutes
const domains = await cache.getOrSet('domains', async () => {
  return await send.domains.list();
}, { ttl: 300 });

3. Monitor Your Usage

Check your rate limit headers and dashboard:

Track X-RateLimit-Remaining in your logs
Set up alerts when approaching limits
Review usage patterns in the dashboard

4. Spread Load Over Time

Instead of sending all emails at once, spread them out:

// Bad: Send all at once
for (const user of users) {
  await send.emails.send({ to: user.email, ... });
}

// Good: Spread over time
for (const user of users) {
  await send.emails.send({ to: user.email, ... });
  await sleep(100); // 100ms between sends
}

Burst Handling

Send.dev allows short bursts above your rate limit for sudden spikes. However, sustained traffic above your limit will trigger rate limiting.

Plan	Burst Allowance
Free	None
Starter	2x for 10 seconds
Pro	3x for 30 seconds
Enterprise	Custom

Daily Limits

Daily email limits reset at midnight UTC. Monitor your usage to avoid hitting daily caps:

curl https://api.send.dev/v1/usage \
  -H "Authorization: Bearer sk_live_your_api_key"

{
  "period": "2025-01-13",
  "emails": {
    "sent": 5420,
    "limit": 10000,
    "remaining": 4580
  },
  "api_requests": {
    "count": 1250,
    "limit": null
  }
}

Upgrading Your Plan

If you're consistently hitting rate limits, consider upgrading:

Go to Settings → Billing
Click Upgrade Plan
Select a plan with higher limits
New limits take effect immediately

Or contact us for enterprise solutions with custom limits.

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