Per-key limits
- Mailbox reads: 120 requests per minute per API key.
- API sends: 30 requests per minute per API key.
Per-account send limit
All sends also pass through the existing per-account limit of 8 messages per minute. The tighter account limit applies even if the API key itself has remaining capacity. Other product and abuse controls may also reject requests.
Handling 429
Honor the `Retry-After` response header. Pause before retrying, use bounded exponential backoff and jitter, and avoid synchronized retry storms. Do not create multiple API keys to evade a limit.
Input and paging bounds
- Read `limit`: 1–100, default 50.
- Read `offset`: 0–10,000, default 0.
- Send recipients: 20 total maximum.
- Send body: 1 MiB maximum.
- Text body: 500,000 characters maximum.
- Key records: 10 active keys per personal Mail account.