curl -X PATCH 'https://api.resend.com/broadcasts/id' \
  -H "Authorization: Bearer $RESEND_API_KEY" \
  -H 'User-Agent: my-app/1.0' \
  -H 'Content-Type: application/json' \
  -d '{
  "name": "string",
  "audience_id": "string",
  "segment_id": "string",
  "from": "string",
  "subject": "string",
  "reply_to": [
    "string"
  ],
  "preview_text": "string",
  "html": "string",
  "text": "string",
  "topic_id": "string"
}'

# PATCH /broadcasts/{id} (Resend API)
Base URL: https://api.resend.com
Auth: Authorization: Bearer <RESEND_API_KEY>
Last verified: 2026-09-03

> Update an existing broadcast

## 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 PATCH 'https://api.resend.com/broadcasts/id' \
  -H "Authorization: Bearer $RESEND_API_KEY" \
  -H 'User-Agent: my-app/1.0' \
  -H 'Content-Type: application/json' \
  -d '{"name":"string","audience_id":"string"}'

## Parameters
| Name | In | Type | Required | Description |
| :--- | :--- | :--- | :--- | :--- |
| id | path | string | Yes | The Broadcast ID. |
| name | body | string | No | Name of the broadcast. |
| audience_id | body | string | No | Use `segment_id` instead. Unique iden... |

## Response (200 OK)
{"id":"78261eea-8f8b-4381-83c6-79fa7120f1cf","object":"broadcast"}

---
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PATCH

/broadcasts/{id}

Resend API

Update an existing broadcast

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
→ 206 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 PATCH 'https://api.resend.com/broadcasts/id' \  -H "Authorization: Bearer $RESEND_API_KEY" \  -H 'User-Agent: my-app/1.0' \  -H 'Content-Type: application/json' \  -d '{  "name": "string",  "audience_id": "string",  "segment_id": "string",  "from": "string",  "subject": "string",  "reply_to": [    "string"  ],  "preview_text": "string",  "html": "string",  "text": "string",  "topic_id": "string"}'

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Parameters

Name	In	Type	Required	Description
id	path	string	Yes	The Broadcast ID.
name	body	string	No	Name of the broadcast.
audience_id	body	string	No	Use `segment_id` instead. Unique identifier of the audience this broadcast will be sent to.
segment_id	body	string	No	Unique identifier of the segment this broadcast will be sent to.
from	body	string	No	The email address of the sender.
subject	body	string	No	The subject line of the email.
reply_to	body	string[]	No	The email addresses to which replies should be sent.
preview_text	body	string	No	The preview text of the email.
html	body	string	No	The HTML version of the message.
text	body	string	No	The plain text version of the message.
topic_id	body	string	No	The topic ID that the broadcast will be scoped to.

Response 200 OK

{
  "id": "78261eea-8f8b-4381-83c6-79fa7120f1cf",
  "object": "broadcast"
}