Limits and quotas
What is capped, and what happens at the cap.
| Limit | Value |
|---|---|
| Recipients per request (to, cc and bcc) | 50 |
| Subject length | 998 characters, no line breaks |
| html or text body | 1,000,000 characters each |
| Request size | 2 MiB |
| Tags per message | 10 (keys: letters, digits, _ . -, up to 64; values up to 256 characters) |
| Requests per second per key | 20, with bursts up to 40 |
| List page size | 1 to 100 |
Rate limit
Every response carries ratelimit-limit (requests per second allowed), ratelimit-remaining (requests left right now) and ratelimit-reset (seconds until the next request is worth trying). Over the limit you get 429 rate_limited with a Retry-After header. Slow down and retry with the same idempotency key. Enterprise accounts can have a higher limit set for the whole organization.
Message retention
We keep the content of your emails for 30 days by default. After that the text and HTML are deleted, and the subject, recipients, status and event history remain. You can choose 7 to 365 days under Settings → Message retention. Mail that has not been sent yet is never deleted.
Monthly allowance and daily limit
Your plan includes a number of emails per month. Sending stops at your limit instead of billing past it, unless you turn on overage and set a spend cap. Free plans have a daily cap too. Each project also has its own daily limit. See Pricing.
Only live sends count. Test projects never deliver and do not count. Use GET /v1/usage to read your numbers.