When I start Thunderbird, new messages are downloaded (it is OK) and marked as not read. The problem is, I have already read them in another application, in fact Thunderbird on another computer. Would it be possible for Thunderbird to "find out" that some messages have been read already and mark them as read? It works on Blue Mail on my Android device. It somehow "knows" that some messages have been read (via Thudderbird on one of my computers) and marks them accordingly as read.