What are the rate limits?

AgentMail is built for high-volume agent workflows. Limits vary by plan.

Sending limits by plan

For full plan details, see the pricing page.

API rate limits

All API endpoints are rate-limited per API key. If you exceed the limit, the API returns a 429 Too Many Requests response with a Retry-After header indicating how long to wait before retrying.

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import { AgentMailClient } from "agentmail";
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const client = new AgentMailClient({ apiKey: "am_..." });
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async function sendWithRetry(inboxId: string, params: any, maxRetries = 3) {
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  for (let attempt = 0; attempt < maxRetries; attempt++) {
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    try {
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      return await client.inboxes.messages.send(inboxId, params);
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    } catch (error: any) {
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      if (error.statusCode === 429 && attempt < maxRetries - 1) {
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        const retryAfter = parseInt(error.headers?.["retry-after"] || "5");
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        await new Promise((r) => setTimeout(r, retryAfter * 1000));
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      } else {
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        throw error;
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      }
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    }
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  }
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}

Tips for high-volume agents

Distribute sends across inboxes. Sending from multiple inboxes improves deliverability and avoids per-address throttling by mailbox providers. Instead of 1,000 emails from 1 inbox, send 10 emails each from 100 inboxes.

Use idempotency keys for resource creation. The clientId parameter on create operations (inboxes, pods, webhooks, drafts) prevents duplicate resources on retries. For preventing duplicate email sends, track sent message IDs in your application or use the draft workflow.

Implement exponential backoff. When you receive a 429 response, wait for the duration specified in the Retry-After header before retrying. Increase the wait time with each consecutive retry.

Monitor your usage. Track your sending volume against your plan limits. You can view usage in the AgentMail Console.

Need higher limits?

If you need higher sending volumes or more inboxes than your current plan allows, contact support@agentmail.cc or visit the pricing page for enterprise options.