@coderus, one thing i noticed, suppose if we send a message to a contact who is offline then we will see light green indicator which i understand says delivered to server. Once contact receives message it turns into dark green indicating message delivered. But before the other contact receives message if we quit persecute, then come back after the message is delivered to contact then the Color still stays as light green, forever. So in reality we will not know if the message successfully delivered.
Also how will we know if a message is not reached the server? Some color indicator like in other clients(red?).