Yup, no in-game messages period. No out-of-game messages, either, if they have anything to do with the game itself.
This game should feel just like single-player, except with thinking opponents and the pleasure of knowing that when you're ________ing someone's _________, there's actually someone squirming on the other end of the line.
Castigated, I'll take you off the list. If anyone else doesn't want to receive notifications, just let me know.
Cheers!