Work with attachments

Download a received fileCopy Anchor Link

Fetch the message detail and wait for processing_status: "ready". Each content.attachments entry supplies an id, filename, size, and MIME metadata. Use the returned ID, not the filename, in the download request:

GET /v1/messages/MESSAGE_ID/attachments/ATTACHMENT_ID HTTP/1.1
Host: cherami.to
Authorization: Bearer YOUR_CREDENTIAL

The response is a download with Content-Type: application/octet-stream. The filename and reported MIME type describe the file; they are not trust signals. Choose a safe local destination rather than treating a sender's filename as a path.

If prepared content failed, you can download /v1/messages/MESSAGE_ID/raw and use your own MIME tools. Incoming mail has a 25 MiB total limit including MIME-encoded attachments.

Attach a file to a sendCopy Anchor Link

Encode the file bytes as padded base64 with no whitespace. Include the result in the ordinary sending request:

{
  "to": ["recipient@example.com"],
  "subject": "Notes",
  "text": "Attached are the notes.",
  "attachments": [
    {"filename": "notes.txt", "type": "text/plain", "content": "SGVsbG8="}
  ]
}

This example attaches the five bytes Hello. Cherami does not fetch attachment URLs or support inline attachments. At most 32 files are allowed. Outbound JSON is capped at 8 MiB; the total email must fit 5 MiB, including generated MIME and attachments. Base64 expands data, so do not assume a 5 MiB file fits.

Retrieve sent attachmentsCopy Anchor Link

GET /v1/sent/MESSAGE_ID includes base64 content in submission.attachments. Decode it to recover the file. Thread detail returns attachment metadata without bytes; use sent detail or the received attachment download when you need the file itself.

Exact attachment validation · Mail safety