Rate limits and quotas
How many requests you can make per second, and how API email counts toward your plan.
Rate limit
The number of API requests an account can make per second depends on its plan, and is shared by all of the account's API keys:
| Plan | Requests per second | Emails per second with batch sending |
|---|---|---|
| Free | 2 | up to 200 |
| Professional | 10 | up to 1,000 |
| Premium | 20 | up to 2,000 |
| Ultra | 50 | up to 5,000 |
| Enterprise | 100 | up to 10,000 |
A plan that is not active (for example an expired subscription) gets the Free limit. An upgrade takes effect within a minute. To send more emails per request, use batch sending: one request carries up to 100 emails. Your monthly email allowance still applies. Authenticated responses include these headers:
| Header | Meaning |
|---|---|
ratelimit-limit | Requests allowed per second. |
ratelimit-remaining | Requests left in the current second. |
ratelimit-reset | Seconds until the limit resets. |
retry-after | On a 429 response: seconds to wait before retrying. |
Over the limit, the API returns 429 rate_limit_exceeded. Wait for retry-after and retry; with an Idempotency-Key the retry is always safe. For a higher limit, upgrade your plan, or email lalit@cresca.xyz.
Requests with a missing, unknown or revoked API key are limited separately: after 60 such requests from one IP address in 15 minutes, further requests from that address get 429 rate_limit_exceeded until the window ends.
Monthly allowance
API email uses the same monthly email allowance as your campaigns. Each recipient (to, cc and bcc) counts as one email. When the allowance runs out, the API returns 429 monthly_quota_exceeded and accepts no more email until the next billing period or an upgrade. See pricing for each plan's allowance.
Recipients that are suppressed, and emails that are canceled or fail before sending, are given back to your allowance.
Size limits
| Limit | Value |
|---|---|
| Recipients per email (to + cc + bcc) | 50 |
| Emails per batch request | 100 |
| Attachments per email | 20, up to 7 MB in total |
| Tags per email | 10 |
| Custom headers per email | 50 |
| Subject | 998 characters, single line |
| Request body | 10 MB |
| Scheduling | Up to 30 days ahead |