For the list, in plain text: IIUC, they use the date received to sort. I think this might stem from a historical cruft: emails sometimes took non-trivial amounts of time to transit, back in the old days. MUAs (especially web-based ones) probably did not want to violate user expectation by placing a new email under several already-read emails. I would argue that this was reasonable behavior. Further, since email is near-instantaneous today, it really makes no difference which way the MUA sorts. Except for git send-email. It might be acceptable to put in a "practical hack" to help out MUAs in the context of "near instant forwarding". I would argue against it on grounds of it being an ugly hack, for very little benefit. The patch that began this thread is also ugly, but has the important consequence of enabling some people to use git send-email at all. p.s- We should probably allow emails from mobile devices on the list. It usually contains a HTML subpart.