An error occurred while saving the commentAnonymous commented
Agree. Furthermore I see that you can mark individual emails as read/unread when you open a conversation. However if you just want to do this for the latest email in the chain, the first option you are presented with is "mark as read". This is backwards. By opening the email, you are already marking as read, so the first option should be "mark as unread" or even more clear, "leave as unread".
Alternatively, you can have a setting where opening the email does not mark as read by default.
Finally, a "swipe" default action like Apples native email would address this issue as well.