Sending message at end of game

If you message your opponent at the end of a game, does the message actually get sent/arrive?  I usually message at the end of a game..."well played", "unlucky" or something more detailed about the game.  However I never get any response unless there has been an earlier exchange of messages during the game.  The same applies in reverse, I never receive any comment after a game unless there has been an earlier exchange.  Is this actually the case, or do other people just never hang around at the end of a game?

I think chat is off by default, so when you post a message, it asks your opponent if he/she wants to chat.

I would guess that most have already started a game review or a new game and that those who are still around don't accept.

Yes, you are right in that you initially get a chat request with the option to accept or decline. I just think that it is nice to acknowledge your opponent, even just to thank them for the game.