Retrieve Received Email Attachment

Retrieve one attachment record for a received email and get a short-lived private download URL.

GET /emails/receiving/{id}/attachments/{attachmentId}

Compatibility note: GET /api/emails/receiving/{id}/attachments/{attachmentId} remains available for existing OpenSend integrations; new API clients can use the root compatibility path above.

Authentication

Use an OpenSend API key in the Authorization header. The key owner must match the received email row.

http

Authorization: Bearer os_YOUR_API_KEY

Path parameters

Name	Type	Description
`id`	string	Received email ID.
`attachmentId`	string	Attachment ID from the attachment list response.

Response

json

{
  "object": "received_email_attachment",
  "id": "att_01",
  "filename": "invoice.pdf",
  "content_type": "application/pdf",
  "size": 1234,
  "download_url": "https://storage.example.com/private-object?...",
  "expires_at": "2026-05-10T13:00:00.000Z"
}

download_url is generated from the private object key saved by your receiving pipeline. OpenSend sets the response expiration one hour after the request time.

Self-hosting notes

Keep the backing bucket private. Do not persist presigned URLs; request a fresh attachment detail response when an agent, workflow, or support tool needs the file.