I'm not sure I understand your request, can you elaborate?

Do you mean the replies you give back to the person? You can click "Board-to-board" and then type your response there, once you press submit you'll see the message you sent. Pressing "board-to-board" will also show you the entire thread/conversation with that other person.

@SamanthaNguyen Yeah I know that. But you cannot see messages you have sent that hasn't been responded.