I can't give a URL but there was a link recently on the top of HN that converted emails to an image that can only be read once before its deleted which means as

I can't give a URL but there was a link recently on the top of HN that converted emails to an image that can only be read once before its deleted which means as soon as the other end reads the email they can do it again, so if their gmail was 'prism-ed' the NSA wouldnt be able to read it.