I concur with your point that in a situation like a blog or Twitter where you don't necessarily care about the contents of previous posts and the information de

I concur with your point that in a situation like a blog or Twitter where you don't necessarily care about the contents of previous posts and the information density is low, top-posting is natural. However, when you DO care about the contents of the previous posts[1], or the information density is higher, I think interleaved posting really starts to shine. When I use email (as opposed to IM, Twitter, etc.) I'm usually discussing technical or business-oriented topics. Precision and context are very important in these discussions, and the emails are often significantly longer than might be common in personal communication. With top-posting, each point or answer is divorced from its context, which can force the reader to jump back and forth in the text to fully understand what's being said, increasing the chances for confusion. Interleaved posting allows me to act as an editor: I remove parts of earlier emails that are irrelevant to the current discussion, group quoted text with the corresponding reply, and add spacing or reorder fragments as needed to improve clarity. I find that in the end, this makes the discussion much easier to follow for the recipient. For me, the bottom line is that when a misunderstanding could waste much more time than it would take me to do a little editing, the interleaved style really makes sense. When I use email, this is usually the case, since I usually use other mediums for personal communication. [1] I can't help but think of this privately as: does this discussion have the Markov property?