The importance is all about within game, if it's isn't than the other methods are fine...I didn't mean a chat feature, only the ability to say "Hey when your thru wait as I'd like to play".....thus that player wouldn't just begin another round.
So if not in game, phone, skype, messenger, dixie cups and string, carrier pigeon all would be fine.
I know CC owners were looking for something, a message box within the screen on the main page......listed under another topic there were a bunch. When wgt's answer was mass email, all ^%$#* broke loose as it didn't come near to addressing the issue.
But I posted my suggestion. Case closed for me......