# PATCH /inboxes/{inbox_id}/drafts/{draft_id} (Resend API)
Base URL: https://api.resend.com
Auth: Authorization: Bearer <RESEND_API_KEY>
Last verified: 2026-10-20

> Update an existing draft

## 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 accepts either a single recipient email address string or an array of strings for multiple recipients (max 50).

## cURL
curl -X PATCH 'https://api.resend.com/inboxes/inbox-id/drafts/draft-id' \
  -H "Authorization: Bearer $RESEND_API_KEY" \
  -H 'User-Agent: my-app/1.0' \
  -H 'Content-Type: application/json' \
  -d '{"to":["ada@example.org"],"cc":"example-cc"}'

## Parameters
| Name | In | Type | Required | Description |
| :--- | :--- | :--- | :--- | :--- |
| inbox_id | path | string | Yes | The Inbox ID or the inbox email addre... |
| draft_id | path | string | Yes | The Draft ID. |
| to | body | string | Yes | The recipients. For multiple addresse... |
Other params: cc, bcc, subject, html, text, attachments

## Response (200 OK)
{"object":"inbox_draft","id":"c3a1e8b4-2d5f-4a7c-9e10-6b8d7f5a4c32"}

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