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
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:
Handling rate limits in your code
Checking your usage
Monitor your current rate limit usage through the dashboard or the delivery metrics API: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.

