My understanding is that I'm supposed to receive this message whenever Skype receives a chat message:

MESSAGE [n] STATUS RECEIVED

and receive this whenever a message is read in Skype client (chat window open):

MESSAGE [n] STATUS RECEIVED

However, I find that if I do not check "open chat window when someone starts a chat", I always receive the RECEIVED messages. But if I have the chat window open, I'll only receive the READ messages, but not the RECEIVED messages. Is this by design? This really makes it difficult to catch all messages from a Skype App because my Skype App doesn't really care if a message has been read by the user. It just wants a reliable way of getting all chat messages. It would make sense to me to always send RECEIVED message (because the message has been received) and send READ message when it's read. Otherwise, the app has to keep track of both types of messages as well as the message IDs, and make sure when it gets a READ message, it won't process the message twice if the chat message has already been processed with the RECEIVED message. And this sometimes means the app has to persist the message IDs in case it is restarted before the messages are read by the skype client. This really makes things unnecessarily complex IMO. Or am I missing something?

A message may be RECEIVED then READ, but never READ and then RECEIVED. You can use this to make your list of messages to keep track of much shorter. If you get a RECEIVED, add it to the list. If you get a READ, search the list and delete the call if it's in there.

RECEIVED is an indication that a message has been received but is unread. You can use the SET CHATMESSAGE SEEN to give make each RECEIVED message a READ message, and only process the READ messages. The problem with this is that your user won't see those messages pop up.

I understand what you are saying. You would still need to persist the message received although it'll be fewer messages.

My point is, if STATUS RECEIVED, by definition, is sent when a message is received, it should always be sent, and thus free the application from having to keep track of the received messages, which makes the app logic unnecessarily complicated. I hope skype engineers see this point and make changes in a future version.

If the chat window is open you will NOT get a received message only a READ message.