Introduction

ToSend is an email sending API that makes it easy to send transactional emails at scale. Built on AWS SES infrastructure, ToSend provides reliable email delivery with comprehensive tracking.

Base URL

https://api.tosend.com

Authentication

All API requests require authentication using an API key. Include your API key in the Authorization header:

Authorization: Bearer your_api_key_here

TIP

You can also send the API key in the request body as api_key. Header authentication is recommended.

{
  "api_key": "your_api_key_here"
}

You can generate API keys from your ToSend dashboard. API keys can be restricted to specific domains for added security.

Response Format

All responses are returned in JSON format.

Success Response

{
  "message_id": "abc123def456..."
}

Error Response

{
  "status_code": 422,
  "error_type": "validation_error",
  "message": "Subject and either html or text content are required.",
  "errors": {
    "subject": {
      "required": "Subject is required."
    }
  }
}

Error Response Fields

Field	Type	Description
status_code	integer	HTTP status code
error_type	string	Machine-readable error category
message	string	Human-readable error message
errors	object	Field-specific validation errors (optional)

Error Types

Error Type	Description
bad_request	Malformed request (400)
unauthorized	Missing API key (401)
forbidden	Invalid API key or insufficient permissions (403)
not_found	Endpoint or resource not found (404)
validation_error	Request validation failed (422)
rate_limit_exceeded	Too many requests (429)
internal_error	Server error (500)

Rate Limits

Rate limits depend on your plan type. Check your account dashboard for current limits.

HTTP Status Codes

Code	Description
200	Success
401	API key missing
403	Invalid API key, insufficient credits, or domain not allowed
422	Validation error
500	Server error