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Rate limits are enforced per-second, per-day, per-inbox, and per-API-key. New inboxes warm up gradually, and sending pauses automatically if bounce or complaint rates spike.

API rate limits

When you exceed the rate limit, the API returns 429 Too Many Requests with a Retry-After header indicating how many seconds to wait.

Rate limit layers

Commune applies rate limits at four levels, each independently enforced:

1. Per-second rate limit

Controls the maximum number of API requests per second per organization. Applies to all endpoints.

2. Daily email limit

Maximum number of outbound emails per day, per organization. Resets at midnight UTC.

3. Inbox daily limit

Per-inbox sending cap that limits how many emails a single inbox can send per day. This is configurable and defaults to your plan’s inbox limit.

4. API key limit

Individual API keys can have custom daily email limits set through the dashboard. Useful for limiting automated systems independently from human-triggered sends.

Burst detection

Beyond per-second rate limits, Commune monitors for abnormal sending spikes. If your sending rate suddenly increases beyond your established pattern, burst detection temporarily throttles sends to protect your domain’s reputation. How it works:
  • Commune tracks your sending velocity over rolling windows
  • A sudden spike (e.g., 10x your normal rate) triggers burst protection
  • Sends are throttled (not rejected) until the rate normalizes
  • No permanent penalty — this is a protective measure
Why this matters: Email providers like Gmail monitor sending patterns. A sudden spike from a domain that normally sends 50 emails/day can trigger spam filters even if the content is legitimate.

Warmup gate

New inboxes start with a lower daily sending limit that gradually increases over time: This follows email industry best practices for “warming up” a new sending identity. Skipping warmup is one of the most common reasons new domains get flagged as spam.
Warmup limits apply per inbox, not per domain. If you create multiple inboxes, each warms up independently.

Sending health gate

If your bounce rate or complaint rate exceeds critical thresholds, Commune automatically pauses outbound sending for the affected inbox: When paused, send attempts return a 403 error:
This automatic protection prevents your domain from being blacklisted by email providers.

Handling rate limits in your code

Checking your usage

Monitor your current rate limit usage through the dashboard or the delivery metrics API:
The sent field in the response tells you how many emails you’ve sent in the period. Compare against your plan’s daily limit to check headroom.

Requesting higher limits

If you need higher rate limits or daily email caps:
  • Pro/Business: Limits can be adjusted through the dashboard billing page
  • Enterprise: Contact us for custom limits tailored to your sending patterns

What’s next?

Delivery Monitoring

Track sent volume, bounce rates, and suppression events.

Spam Prevention

Outbound content validation and inbound spam scoring.

Authentication

Set per-key daily limits to restrict automated senders.

Security Overview

Full picture of Commune’s security and protection layers.
Last modified on March 19, 2026