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Documentation Index

Fetch the complete documentation index at: https://resend.com/docs/llms.txt

Use this file to discover all available pages before exploring further.

When someone sends an email with file attachments, the adapter makes them available on message.raw.attachments. Each attachment includes the filename, MIME type, and a URL to download the content.

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Attachment shape

interface ResendAttachment {
  filename: string;
  contentType: string;
  url?: string;
}
FieldTypeDescription
filenamestringOriginal filename (e.g., invoice.pdf)
contentTypestringMIME type (e.g., application/pdf)
urlstringOptional download URL for the attachment content

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Detecting and processing attachments

chat.onNewMention(async (thread, message) => {
  const attachments = message.raw?.attachments ?? [];

  if (attachments.length === 0) {
    await thread.subscribe();
    await thread.post('Got your email — no attachments found.');
    return;
  }

  const summary = attachments
    .map((a) => `${a.filename} (${a.contentType})`)
    .join(', ');

  await thread.subscribe();
  await thread.post(`Received ${attachments.length} attachment(s): ${summary}`);
});
For more on receiving email attachments outside the Chat SDK, see Receiving Attachments.

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Try it yourself

Attachments Example

Detects attachments and replies with a summary