Adding Email Attachment

You can add attachment as properties->"$attachments". Attachments can be passed as base-64 file (allowed size limit for base-64 file < 50KB) or directly as the media URL.

// adding base-64 file (supported limit < 50KB)

{
  "properties": {
    "$attachments": [
      {
        "filename": "billing.pdf",
        "contentType": "application/pdf",
        "data": "Q29uZ3JhdHVsYXRpb25zLCB5b3UgY2FuIGJhc2U2NCBkZWNvZGUh" // this is base64 encoded content
      }
    ]
  }
}


// adding URL directly (no limit on the file size)

{
  "properties": {
    "$attachments": [
      {
        "filename": "Bitcoin-whitepaper.pdf", // optional. if not present, filename will be picked from the url
        "url": "https://bitcoincore.org/bitcoin.pdf",
        "ignore_if_error": true/false
      }
    ]
  }
}