Like in a web browser if we could go back to the previous page (conversation in this case) it would be pretty usefull for merging and "linking" conversation together.
Open Message in inbox if messaged received while sending and archiving
I have missed dozens of important messages because I hit "send and archive" and the client replys back while that is happening. The archive overrides it and I never see the new message until I get a reminder from client or I go looking for it.