@HarryT: IMO uploading a book for debugging purposes, while keeping it only privately shareable is just as much fair use as uploading an extract from one. In fact, I would argue that it is much more unambiguously fair use, since when dealing with extracts there is the question of how much of an extract is allowed, 1%, 10%, 90%? before it loses fair use protection. And MR has always allowed extracts. In fact, the MR server could auto-delete such attachments after a period of a couple of days, for added safety.
@jackie_w: Indeed, using PMs is a tad more cumbersome than sharing publicly, but, creating a calibre plugin, will limit the solution to only users of calibre, which is fine by me, personally, but I was trying for an MR wide solution
