&gt; inline replies to parts of messages to enable nested conversations.<p>Just to be sure: You know that that is really easy with email as it existed until about 20 years ago, including BBS networks, usenet, etc., and that it is still trivial with good email clients? That was a solved problem that made email really efficient, until some clueless developers and users came along and disinvented (is that a word?) the solution in order to make email easy to use (or so they claimed).