Forward Thread Email

Forward a message in an inbox thread to new recipients.

Inboxes are currently in private beta and only available to a limited number of users. The response shape might change before GA.

Get early access if you're interested in testing this feature.

Once you have access, upgrade your Resend SDK to use the new methods:

Node.js

npm install resend@6.28.1-preview-inboxes.2

CLI

npm install -g resend-cli@2.22.0-preview-inboxes.2

Forwards from the inbox address. to is required. The original message is quoted under a forwarded-message banner.

Path Parameters

The Inbox ID.

The Thread ID.

The Email ID of the message to forward, as returned in the thread's messages[].id.

Body Parameters

to (string | string[], required) — Recipient email address. For multiple addresses, send as an array of strings. Max 50.
html (string) — An HTML note sent above the quoted original.
text (string) — A plain-text note sent above the quoted original.
subject (string) — The subject of the forward. When omitted, the thread subject is used, prefixed with Fwd: if it isn't already.

Response Fields

id (string) — The ID of the queued outbound email.
email_id (string) — The ID of the queued outbound email. Same value as id.
direction (string) — Always outbound.
from (string) — Sender email address.
to (string[]) — The recipients of the message.
cc (string[]) — The CC recipients of the message.
bcc (string[]) — The BCC recipients of the message.
reply_to (string[]) — Always an empty array.
subject (string) — The subject of the sent forward.
message_id (string | null) — Always null.
html (string) — The HTML body, including the note and the quoted original.
text (string) — The plain-text body, including the note and the quoted original.
attachments (array) — The attachments on the message.
properties
- id (string) — The ID of the attachment.
- filename (string | null) — The filename of the attachment.
- size (number | null) — The size of the attachment in bytes.
read (boolean) — Whether the message has been read.
received_at (string) — ISO 8601 timestamp when the message was sent.

Node.js

import { Resend } from 'resend';

const resend = new Resend('re_xxxxxxxxx');

const { data, error } = await resend.inboxes.threads.emails.forward({
  inboxId: 'b3e2b2b6-3f0e-4c8e-9ad3-2f43a1e2c7f1',
  threadId: '4d8e2a1c-9b3f-4c6d-8a21-3e5f7c9c0d12',
  emailId: '5b1a9f47-2c8d-4e6f-9a03-1d2e3f4a5b60',
  to: ['colleague@example.org'],
  text: 'Flagging this refund request for you.',
});

cURL

curl -X POST 'https://api.resend.com/inboxes/b3e2b2b6-3f0e-4c8e-9ad3-2f43a1e2c7f1/threads/4d8e2a1c-9b3f-4c6d-8a21-3e5f7c9c0d12/emails/5b1a9f47-2c8d-4e6f-9a03-1d2e3f4a5b60/forward' \
     -H 'Authorization: Bearer re_xxxxxxxxx' \
     -H 'Content-Type: application/json' \
     -d $'{
  "to": ["colleague@example.org"],
  "text": "Flagging this refund request for you."
}'

CLI

resend inboxes threads emails forward \
  --inbox_id b3e2b2b6-3f0e-4c8e-9ad3-2f43a1e2c7f1 \
  --thread_id 4d8e2a1c-9b3f-4c6d-8a21-3e5f7c9c0d12 \
  --email_id 5b1a9f47-2c8d-4e6f-9a03-1d2e3f4a5b60 \
  --to colleague@example.org \
  --text "Flagging this refund request for you."

Response

{
  "id": "6a0c8e58-3d9e-4f7a-8b14-2e3f4a5b6c71",
  "email_id": "6a0c8e58-3d9e-4f7a-8b14-2e3f4a5b6c71",
  "direction": "outbound",
  "from": "support@example.com",
  "to": ["colleague@example.org"],
  "cc": [],
  "bcc": [],
  "reply_to": [],
  "subject": "Fwd: Refund for order 1041",
  "message_id": null,
  "html": "<div>Flagging this refund request for you.<br>\n<br>\n---------- Forwarded message ---------<br>\nFrom: Ada Lovelace &lt;ada@example.org&gt;<br>\nDate: Wed, Aug 5, 2026 at 2:03 PM<br>\nSubject: Refund for order 1041<br>\nTo: support@example.com<br>\n<br>\nCould I get a refund for order 1041?</div>",
  "text": "Flagging this refund request for you.\n\n---------- Forwarded message ---------\nFrom: Ada Lovelace <ada@example.org>\nDate: Wed, Aug 5, 2026 at 2:03 PM\nSubject: Refund for order 1041\nTo: support@example.com\n\nCould I get a refund for order 1041?",
  "attachments": [],
  "read": true,
  "received_at": "2026-08-05T14:12:04.110Z"
}