Resend 429 daily_quota_exceeded or monthly_quota_exceeded: email quota hit

TL;DR: A 429 with daily or monthly quota exceeded is about email volume, not request rate. The daily quota only exists on the Free plan and resets at midnight UTC, not on a rolling window. Confirm the cause: this is a volume quota, distinct from the per-second rate limit. Check the x-resend-daily-quota and x-resend-monthly-quota response headers to see your usage.

The error

sends return 429 with error type daily_quota_exceeded ("You have exceeded your daily email sending quota") or monthly_quota_exceeded.

The fix

1. Confirm the cause: this is a volume quota, distinct from the per-second rate limit. Check the x-resend-daily-quota and x-resend-monthly-quota response headers to see your usage.
2. Know the reset rules: the daily quota applies only to the Free plan. It runs on a UTC calendar day (00:00 to 24:00 UTC) and resets at midnight UTC. It is not a rolling 24-hour window, so "it has been 24 hours" does not clear it.
3. Count correctly: both sent and received emails count toward the quotas, so inbound mail consumes your budget too.
4. Fix: for a daily quota hit, wait until midnight UTC, or upgrade the plan to remove the daily quota. For a monthly quota hit, upgrade the plan to raise the monthly limit.
5. Verify: after reset or upgrade, resend and confirm a 200 with an email id. Set up monitoring on the quota headers so a scheduled job does not discover the limit at 2am.

When to use this

• You are seeing this exact error message; match the block above, not just part of it.
• The failing call matches the scenario in the title: Resend 429 dailyquotaexceeded or monthlyquotaexceeded.
• You want the fastest verified fix before digging through logs.

When not to use this

• Your error text differs from the block above; close cousins often have different causes.
• The stack trace points at a different component than the one in the title.
• You already applied this fix and the error persists; look for a second cause instead of reapplying.

Compatibility

• Not pinned to a specific version; follows current Resend behavior.

Documented in Resend docs: 429 dailyquotaexceeded and monthlyquotaexceeded; daily quota is Free plan only, UTC calendar day resetting at midnight UTC; both sent and received emails count; tracked via x-resend-daily-quota and x-resend-monthly-quota headers. Evidence: resend.com/docs/api-reference/rate-limit and resend.com/docs/api-reference/errors.