curl -X PATCH 'https://api.resend.com/contacts/contact-id/topics' \
  -H "Authorization: Bearer $RESEND_API_KEY" \
  -H 'User-Agent: my-app/1.0' \
  -H 'Content-Type: application/json' \
  -d '{
  "topics": [
    {
      "id": "string",
      "subscription": "opt_in"
    }
  ]
}'

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

> Update topics for a contact

## 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/contacts/contact-id/topics' \
  -H "Authorization: Bearer $RESEND_API_KEY" \
  -H 'User-Agent: my-app/1.0' \
  -H 'Content-Type: application/json' \
  -d '{"topics":[{"id":"string","subscription":"opt_in"}]}'

## Parameters
| Name | In | Type | Required | Description |
| :--- | :--- | :--- | :--- | :--- |
| contact_id | path | string | Yes | The Contact ID or email address. |
| topics | body | object[] | Yes | Request body field topics. |

## Response (200 OK)
{"object":"contact_topics","contact_id":"string","topics":[{"id":"string","subscription":"opt_in"}]}

---
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PATCH

/contacts/{contact_id}/topics

Resend API

Update topics for a contact

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
→ 192 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/contacts/contact-id/topics' \  -H "Authorization: Bearer $RESEND_API_KEY" \  -H 'User-Agent: my-app/1.0' \  -H 'Content-Type: application/json' \  -d '{  "topics": [    {      "id": "string",      "subscription": "opt_in"    }  ]}'

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Parameters

Name	In	Type	Required	Description
contact_id	path	string	Yes	The Contact ID or email address.
topics	body	object[]	Yes	Request body field topics.

Response 200 OK

{
  "object": "contact_topics",
  "contact_id": "string",
  "topics": [
    {
      "id": "string",
      "subscription": "opt_in"
    }
  ]
}