I know that the Google Drive SDK does not show the user email in the value field of the permission object due to privacy concerns. If we don’t have that user email address, is there a way to know if a document is shared with anyone outside of the domain?
Also, wouldn’t retrieving permissions using the document’s owner authentication allow us to see that email address?
You cannot do that using Drive API. However, you can achieve this result using the old and deprecated Gdata DocumentList API