It would be great if Sinosend provided a "secure send" option for PDF documents. This option would do the following:
  1. Display the file in an online PDF viewer.
  2. Disallow the user from downloading the file.
  3. Disable right-click copy functionality in the browser window.
  4. Embed a watermark containing the recipient's name and email address, displayed multiple times in large type diagonally across every page of the document.
  5. Allow for customization of the watermark to add additional text. The custom watermark input could support placeholders for the recipient's name and email address.