Rate Limits
API requests are rate-limited per organization using a sliding window algorithm.
API requests are rate-limited per organization using a sliding window algorithm.
| Requests | 100 |
| Window | 10 seconds |
| Algorithm | Sliding window |
| Scope | Per organization |
When the rate limit is exceeded, the API returns a 429 Too Many Requests
response with error code RATE_LIMITED. Back off and retry after a short delay.
Email send limits
In addition to the API rate limit, each plan has a monthly email send quota.
Exceeding it returns a 429 with code MONTHLY_LIMIT_EXCEEDED.
Daily send ramp
New accounts start with a lower daily ceiling that increases automatically as the
account ages and sends cleanly, so a newly created account can't send at full
volume on day one. No action is required — after about 7 days paid accounts
graduate to a higher, usage-based daily ceiling (derived from your monthly plan
and recent volume — not a fixed per-tier number, and never unlimited). The Free
plan stays at 100 emails/day. The ceiling counts recipients (to + cc + bcc), the
same unit as billing. Exceeding it returns a 429 with code
DAILY_LIMIT_EXCEEDED; it resets at midnight UTC.
| Account age | Daily limit (paid plans) |
|---|---|
| First 24 hours | 2,000 |
| 1–3 days | 10,000 |
| 3–7 days | 50,000 |
| 7+ days (established) | Usage-based* |
*Established accounts are bounded by a finite, usage-based ceiling — the larger of your monthly limit spread over 30 days and a multiple of your recent busy-day volume. It grows with genuine sending but is never unlimited, so age alone can't unlock your full monthly quota in a single day.
If an account's recent bounce or complaint rate is elevated, its daily ceiling is
automatically halved until the rate recovers. Need a higher limit sooner than the
ramp allows? Email support@eusend.dev and we can raise it manually.