Limits & Quotas
Overview of API rate limits, request payload limits, and account caps.
Devner does not impose a sending quota of its own. The caps below are structural or come from the upstream provider (Google, Microsoft), and the provider's limit is what applies.
API Rate Limits
| Endpoint | Limit | Window | Keyed By |
|---|---|---|---|
POST /api/send | 300 req | per minute | API key |
When a rate limit is hit, the API returns 429 Too Many Requests with a Retry-After header indicating how many seconds to wait.
Request Payload Limits
| Field | Limit | Notes |
|---|---|---|
subject | 998 chars | RFC 2822 maximum |
html | 5 MB | UTF-8 encoded |
text | 2 MB | UTF-8 encoded |
to / cc / bcc | 50 each | String or array of strings |
attachments | 20 files · 10 MB/file | Base64-encoded. 25 MB total cap enforced by Gmail. |
Account & Daily Limits
| Resource | Limit | Notes |
|---|---|---|
| Connected Mailboxes | 50 per provider | 50 Gmail and 50 Microsoft, per Devner user account |
| Active API Keys | 100 | Per Devner user account |
| Devner Sending Quota | None | No monthly, daily, or per-burst cap is enforced by Devner |
| Email Log Retention | 90 days | Logs are automatically deleted after this period |
Personal Gmail (@gmail.com) | Up to 500 emails / day | Google's hard cap, not a Devner limit |
| Google Workspace Account | Up to 2,000 emails / day | Google's hard cap, not a Devner limit |
| Microsoft 365 Mailbox | Tenant-configurable | Set by your Exchange Online recipient limits |
Per-mailbox send caps are enforced by the upstream provider: Google for Gmail, and your Exchange Online tenant for Outlook. Devner spreads sends across the mailboxes you attach to an API key, which lowers the chance of any single mailbox hitting its provider limit. If you exceed a provider limit, that mailbox is rejected and Devner moves to the next one.