curl -X POST 'https://api.resend.com/emails' \
  -H "Authorization: Bearer $RESEND_API_KEY" \
  -H 'User-Agent: my-app/1.0' \
  -H 'Content-Type: application/json' \
  -H 'Idempotency-Key: string' \
  -d '{
  "from": "string",
  "to": "string",
  "subject": "string",
  "bcc": "string",
  "cc": "string",
  "reply_to": "string",
  "html": "string",
  "text": "string",
  "template": {
    "id": "string",
    "variables": {
      "variableName": "Sign up now",
      "variableName2": 123
    }
  },
  "headers": {},
  "scheduled_at": "string",
  "attachments": [
    {
      "content": "binary",
      "filename": "string",
      "path": "string",
      "content_type": "string",
      "content_id": "string"
    }
  ],
  "tags": [
    {
      "name": "string",
      "value": "string"
    }
  ],
  "topic_id": "string"
}'

# POST /emails (Resend API)
Base URL: https://api.resend.com
Auth: Authorization: Bearer <RESEND_API_KEY>
Last verified: 2026-09-03

> Send an email

## Critical Gotchas
* All requests must include a `User-Agent` header (e.g. `User-Agent: my-app/1.0`) or the API returns HTTP 403.
* The `to` field is an array of strings, even when sending to a single recipient.

## cURL
curl -X POST 'https://api.resend.com/emails' \
  -H "Authorization: Bearer $RESEND_API_KEY" \
  -H 'User-Agent: my-app/1.0' \
  -H 'Content-Type: application/json' \
  -H 'Idempotency-Key: string' \
  -d '{"from":"string","to":"string"}'

## Parameters
| Name | In | Type | Required | Description |
| :--- | :--- | :--- | :--- | :--- |
| from | body | string | Yes | Sender email address. To include a fr... |
| to | body | string | Yes | Recipient email address. For multiple... |
| subject | body | string | Yes | Email subject. |

## Response (200 OK)
{"id":"string"}

---
Need an API key? Get one at https://resend.com/signup

POST

/emails

Resend API

Send an email

Base URL: https://api.resend.com
Auth: Authorization: Bearer <RESEND_API_KEY>
Last verified: 2026-09-03 · upstream hash matched

Actions

Agents: curl -H "Accept: text/markdown" this URL
→ 212 tokens · Vary: Accept

Critical gotchas

All requests must include a User-Agent header (e.g. User-Agent: my-app/1.0) or the API returns HTTP 403.

The to field is an array of strings, even when sending to a single recipient.

cURL

curl -X POST 'https://api.resend.com/emails' \  -H "Authorization: Bearer $RESEND_API_KEY" \  -H 'User-Agent: my-app/1.0' \  -H 'Content-Type: application/json' \  -H 'Idempotency-Key: string' \  -d '{  "from": "string",  "to": "string",  "subject": "string",  "bcc": "string",  "cc": "string",  "reply_to": "string",  "html": "string",  "text": "string",  "template": {    "id": "string",    "variables": {      "variableName": "Sign up now",      "variableName2": 123    }  },  "headers": {},  "scheduled_at": "string",  "attachments": [    {      "content": "binary",      "filename": "string",      "path": "string",      "content_type": "string",      "content_id": "string"    }  ],  "tags": [    {      "name": "string",      "value": "string"    }  ],  "topic_id": "string"}'

Get a free Resend API key → sponsored

Parameters

Name	In	Type	Required	Description
from	body	string	Yes	Sender email address. To include a friendly name, use the format "Your Name <sender@domain.com>".
to	body	string	Yes	Recipient email address. For multiple addresses, send as an array of strings. Max 50.
subject	body	string	Yes	Email subject.
bcc	body	string	No	Bcc recipient email address. For multiple addresses, send as an array of strings.
cc	body	string	No	Cc recipient email address. For multiple addresses, send as an array of strings.
reply_to	body	string	No	Reply-to email address. For multiple addresses, send as an array of strings.
html	body	string	No	The HTML version of the message.
text	body	string	No	The plain text version of the message.
template	body	object	No	Use a published template to send the email. If provided, do not include html or text.
headers	body	object	No	Custom headers to add to the email.
scheduled_at	body	string	No	Schedule email to be sent later. The date should be in ISO 8601 format.
attachments	body	object[]	No	Request body field attachments.
tags	body	object[]	No	Request body field tags.
topic_id	body	string	No	The topic ID to scope the email to. If the recipient is a contact and opted-in to the topic, the email is sent. If opted-out, the email is not sent. If the recipient is not a contact, the email is sent if the topic's default subscription is opt_in.

Response 200 OK

{
  "id": "string"
}