GET /messages/:mid/documents/:idx

Retrieves the binary payload of a document stored in a specific message using the index number of the document. The document index is a zero-based index whose first element is always the core document of the message.

To find the document index number, use the GET /messages/:mid call. The call returns a JSON object that represents the message envelope. The index number is found in the index property of each document in the documents array.