Marking a single message unread marks the entire thread
Take a single message in a thread and mark it unread suddenly on your outlook or OWA the entire thread is marked unread.
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.
This is a real chore. If I read an email on my mobile I often mark it as unread if I want to be reminded to follow it up from my office. But in doing so, every message in the thread is changed and this makes it really difficult to keep my inbox tidy and up to date. Please address this Microsoft!!