Concepts
API limits
Plan requests around RouteKite’s payload, content, and attachment limits.
On this page
Email request limits
| Item | Limit |
|---|---|
| Recipient | Exactly one per request |
| Request body | 16,000,000 bytes |
| Subject | 1 to 998 characters |
| HTML | 500,000 characters |
| Plain text | 200,000 characters |
| Idempotency key | 8 to 200 characters |
| Metadata key | 80 characters |
| Metadata string | 500 characters |
Attachment limits
| Item | Limit |
|---|---|
| Files per email | 10 unique attachments |
| Direct file | 5,000,000 decoded bytes |
| Uploaded file | 10,000,000 bytes |
| Combined files | 10,000,000 decoded bytes |
| Upload instruction | 2 hours |
| Direct safety retention | 7 days maximum |
| Uploaded automatic retention | 31 days after completion |
Supported attachment formats
- CSV, DOC, DOCX, GIF, JPEG, JSON, PDF, PNG
- PPT, PPTX, TXT, WEBP, XLS, XLSX, ZIP
- HTML, SVG, scripts, executables, mismatched extensions, and malformed files are rejected.