Error codes

rate_limit_exceeded

You're over your per-minute request rate limit.

Status: 429 · Code: rate_limit_exceeded

You've made more requests in the last 60 seconds than your plan allows.

How it works

Rate limits are per-workspace per-minute
Free: 100 req/min · Growth: 500 req/min · Scale: 2000 req/min
Send and read buckets are separate — bulk GET /emails won't eat your send quota

Every response includes these headers:

X-RateLimit-Limit: 500
X-RateLimit-Remaining: 34
X-RateLimit-Reset: 1712922000
Retry-After: 27     (only on 429)

How to fix

Back off and retry. Retry-After tells you how many seconds to wait. Don't hammer.
Use the SDK's built-in retry — it respects Retry-After automatically.
Batch work up. A for-loop with 10 concurrent sends is fine; 500 concurrent usually hits the limit.
Still not enough? Upgrade the workspace or email support@send0.dev — we raise limits case by case.

Retries use exponential backoff with jitter; bare retries on a 429 will keep you at the limit forever.

Rate limits

template_not_found

The template_id doesn't exist on your workspace.

insufficient_credits

You've hit your workspace's monthly send limit.

On this page

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