Email Sending API docs
Send transactional and marketing emails via API. HTML templates, attachments, and delivery tracking included.
Authentication
All Email Sending API requests authenticate via two headers. Get your API key from your RapidAPI dashboard after subscribing on the Basic (free) tier or higher.
X-RapidAPI-Key: YOUR_API_KEY X-RapidAPI-Host: email-sending-by-helix-api.p.rapidapi.com
Base URL
https://email-sending-by-helix-api.p.rapidapi.com
Endpoints
POST
/sendSend an email
POST
/send/templateSend from HTML template
Code Examples
Python
import requests
url = "https://email-sending-by-helix-api.p.rapidapi.com/send"
headers = {
"X-RapidAPI-Key": "YOUR_API_KEY",
"X-RapidAPI-Host": "email-sending-by-helix-api.p.rapidapi.com",
}
response = requests.post(url, headers=headers)
print(response.json())JavaScript
const response = await fetch(
"https://email-sending-by-helix-api.p.rapidapi.com/send",
{
method: "POST",
headers: {
"X-RapidAPI-Key": "YOUR_API_KEY",
"X-RapidAPI-Host": "email-sending-by-helix-api.p.rapidapi.com"
}
}
);
const data = await response.json();cURL
curl -X POST "https://email-sending-by-helix-api.p.rapidapi.com/send" \ -H "X-RapidAPI-Key: YOUR_API_KEY" \ -H "X-RapidAPI-Host: email-sending-by-helix-api.p.rapidapi.com"
Response Format
All endpoints return JSON in this consistent envelope:
{
"status": "ok",
"data": { /* endpoint-specific payload */ },
"meta": {
"cached": false,
"latency_ms": 142,
"request_id": "req_abc123"
},
"timestamp": "2026-05-21T12:00:00Z"
}Error Codes
| HTTP | Code | Meaning |
|---|---|---|
| 400 | BAD_REQUEST | Missing or invalid parameter |
| 401 | UNAUTHORIZED | Invalid or missing API key |
| 403 | FORBIDDEN | Your plan doesn't include this endpoint |
| 429 | RATE_LIMIT_EXCEEDED | Too many requests — back off and retry |
| 500 | INTERNAL_ERROR | Something went wrong on our side |
| 503 | UPSTREAM_UNAVAILABLE | A third-party data source is down |
Common Use Cases
Transactional emails
Welcome emails
Password resets
Notifications
Marketing blasts
Order confirmation emails
Shipping update emails
Invoice delivery emails
Appointment reminder emails
Two-factor authentication codes
Subscription renewal reminders
Event RSVP confirmations
Abandoned cart recovery emails
Account verification emails
Weekly digest emails
Refund confirmation emails
Trial expiration warnings
Waitlist notification emails
Feedback request emails
Team invitation emails