Rate limits

The API limits requests per second per team (not per key):

Plan	Requests per second
Free	10
Pro	10
Scale	25
Enterprise	Custom

Resend’s limit is 2 requests per second. A batch of up to 100 emails is one request, so you can send thousands of emails per second within the limit.

Limits are applied in one-second windows. Dashboard sessions are not rate limited. Sending quotas (Plans and quotas) are separate from request limits.

Headers

Every response includes:

Header	Meaning
`ratelimit-limit`	Requests allowed per window (for example `10`).
`ratelimit-remaining`	Requests left in the current window.
`ratelimit-reset`	Seconds until the window resets (`1`).
`retry-after`	Only on `429`: seconds to wait before retrying (`1`).

HTTP/1.1 429 Too Many Requests
ratelimit-limit: 10
ratelimit-remaining: 0
ratelimit-reset: 1
retry-after: 1

{ "statusCode": 429, "name": "rate_limit_exceeded", "message": "Too many requests. You can only make 10 requests per second." }

import { SpacePost, type SendEmailOptions } from "@spacepost/node";

const spacepost = new SpacePost();

async function sendWithRetry(email: SendEmailOptions, key: string, attempts = 5) {
  for (let i = 0; i < attempts; i++) {
    const { data, error } = await spacepost.emails.send(email, { idempotencyKey: key });
    if (!error) return data;
    if (error.name !== "rate_limit_exceeded") throw new Error(`${error.name}: ${error.message}`);
    await new Promise((r) => setTimeout(r, 1000 * (i + 1)));
  }
  throw new Error("rate limited");
}

import time, requests

def post_with_retry(url, headers, json, attempts=5):
    for _ in range(attempts):
        r = requests.post(url, headers=headers, json=json, timeout=15)
        if r.status_code != 429:
            return r
        time.sleep(float(r.headers.get("retry-after", 1)))
    return r

Always reuse the same Idempotency-Key on retries so a request that actually succeeded is not repeated.

Tips

Prefer batches over many single sends.
Queue sends in a background worker and cap its concurrency to your limit.
Spread import jobs (for example creating contacts) at a steady pace.