Docs API keys

API keys

Create a domain-scoped key and send it only from your server.

Guide 03

Format HTTPS JSON

Sending uses the X-API-Key header. Keys are created in the dashboard after a domain is verified.

Rules

One key is bound to one verified sending domain
The secret is shown once at creation
Store it in your server environment, not in a browser app
Revoke a leaked key in the dashboard and create a new one

X-API-Key: ep_live_…

Failed auth returns JSON with an error message. Typical statuses: 401 invalid key, 403 unverified account or missing permission, 429 rate limited.

Permissions

Dashboard members with Developer access can send. Billing pages require billing.read / billing.manage. The API still enforces permissions even if the UI hides a screen.

Example request

Live request shape

POST /api/v1/emails

curl -X POST https://api.resendermail.com/api/v1/emails \
  -H "X-API-Key: ep_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "from": "hello@yourdomain.com",
    "to": ["customer@example.com"],
    "subject": "Hello from ResenderMail",
    "html": "<p>Hello</p>"
  }'

const res = await fetch(
  "https://api.resendermail.com/api/v1/emails",
  {
    method: "POST",
    headers: {
      "X-API-Key": "ep_live_...",
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      from: "hello@yourdomain.com",
      to: ["customer@example.com"],
      subject: "Hello from ResenderMail",
      html: "<p>Hello</p>",
    }),
  }
);
const { id, status } = await res.json();

import requests

resp = requests.post(
    "https://api.resendermail.com/api/v1/emails",
    headers={
        "X-API-Key": "ep_live_...",
        "Content-Type": "application/json",
    },
    json={
        "from": "hello@yourdomain.com",
        "to": ["customer@example.com"],
        "subject": "Hello from ResenderMail",
        "html": "<p>Hello</p>",
    },
)
data = resp.json()

using var client = new HttpClient();
client.DefaultRequestHeaders.Add("X-API-Key", "ep_live_...");

using var content = new StringContent(
    """{"from":"hello@yourdomain.com","to":["customer@example.com"],"subject":"Hello from ResenderMail","html":"<p>Hello</p>"}""",
    Encoding.UTF8,
    "application/json"
);
var res = await client.PostAsync(
    "https://api.resendermail.com/api/v1/emails",
    content
);

var client = HttpClient.newHttpClient();
var req = HttpRequest.newBuilder()
    .uri(URI.create("https://api.resendermail.com/api/v1/emails"))
    .header("X-API-Key", "ep_live_...")
    .header("Content-Type", "application/json")
    .POST(HttpRequest.BodyPublishers.ofString("""
        {"from":"hello@yourdomain.com","to":["customer@example.com"],"subject":"Hello from ResenderMail","html":"<p>Hello</p>"}
        """))
    .build();
var res = client.send(req, HttpResponse.BodyHandlers.ofString());

payload := strings.NewReader("{\"from\":\"hello@yourdomain.com\",\"to\":[\"customer@example.com\"],\"subject\":\"Hello from ResenderMail\",\"html\":\"<p>Hello</p>\"}")
req, err := http.NewRequest(http.MethodPost, "https://api.resendermail.com/api/v1/emails", payload)
if err != nil {
    log.Fatal(err)
}
req.Header.Set("X-API-Key", "ep_live_...")
req.Header.Set("Content-Type", "application/json")
res, err := http.DefaultClient.Do(req)

Example response

Response shape

200 api.resendermail.com

{
  "id": "em_4f2c…",
  "status": "queued"
}

Reference

Auth X-API-Key
Format application/json
Base URL https://api.resendermail.com