Resend API (unofficial showcase)
POST/inboxes/{inbox_id}/threads/{thread_id}/emails/{email_id}/forward

Forward an email from a thread

Submits a forward of a message from the inbox address directly, without storing a draft. Supply to recipients and optionally add a note with html or text; the original message is quoted and its attachments are included. Added attachments share the original message's limit of 10 files and 25 MB of content.

  • IdempotentThe SDK sends Idempotency-Key, so a retried request is only applied once.

4 parameters · 8 body fields
inbox_idstringrequired
The UUID of the inbox containing the thread; an email address is not accepted.
thread_idstringrequired
The UUID of the thread containing the message to forward.
email_idstringrequired
The UUID of the message to forward, as returned by the list thread emails endpoint.
Idempotency-Keystringoptional
A unique key to prevent duplicate forwards; retries with the same key within 24 hours return the first successful response. If supplied, the key must be 1 to 256 characters.

Forward recipients, optional note, and optional additional attachments and headers. The original message is quoted, and its attachments are included in the forward.

tostringrequired
Recipient email address. For multiple addresses, send as an array of strings. Must name at least one address. `to`, `cc` and `bcc` combined cannot exceed 50 recipients. Each address is `email@example.com` or `Name <email@example.com>`. An address that is not valid returns a 422.
ccstringoptional
CC recipient email address. For multiple addresses, send as an array of strings. Counts toward the 50-recipient limit. Each address is `email@example.com` or `Name <email@example.com>`. An address that is not valid returns a 422.
bccstringoptional
BCC recipient email address. For multiple addresses, send as an array of strings. Counts toward the 50-recipient limit. Each address is `email@example.com` or `Name <email@example.com>`. An address that is not valid returns a 422.
htmlstringoptional
An HTML note sent above the quoted original.
textstringoptional
A plain-text note sent above the quoted original.
subjectstringoptional
The subject of the forward. Cannot be only whitespace or contain a line break. When omitted, the thread subject is used, prefixed with `Fwd:` if it does not already start with it.
attachmentsarrayoptional
Files to attach, as on `POST /emails`. Each one needs `content` or `path`. They share one limit with the attachments of the original message, which the forward also sends. Together they can have up to 10 files and at most 25 MB of `content`. A `path` file counts toward the 10 files only, because it is fetched when the email is sent. An empty file, a blocked file type, a `path` that is not an `http` or `https` URL or that points to `localhost`, `127.0.0.1` or `0.0.0.0`, or a `content_type` that is not a valid MIME type returns a 422.
headersobjectoptional
Custom headers to add to the email. The `In-Reply-To`, `References` and `Reply-To` headers are set by Resend and cannot be set here. Sending one of them, in any letter case, returns a 422. Header names cannot be empty, and names and values cannot contain line breaks or null characters, or the request returns a 422. `null` means no custom headers.

1 status code
200Returns the sent email's ID, which you can use with the emails endpoints.
idstringrequired
The ID of the sent email. Use it with the emails endpoints.

Error handling

The inbox_id, thread_id, and email_id path parameters must be UUIDs identifying the message to forward. The Idempotency-Key header, if supplied, must contain 1 to 256 characters. Provide at least one address in to; the combined to, cc, and bcc recipients cannot exceed 50, and each address must be a valid email address. The original message's attachments and any added attachments together must not exceed 10 files or 25 MB of content; original attachments sent from a URL cannot be forwarded.