I have at least 4 birds delivering mail to me, but I can't access them to read or reply. People have stated to go to the Main Menu > Check Members > then Check Mail is under Check Friendship Level, but I don't have any other option in there besides the Check Friendship Level.
I think you have to go to check members and and then check mail or you could just fiddle around the pause menu, I'm sorry this is all the info I can give you I haven't played this game in a while and can't play it again since I traded it for another game
"Ah, yes the past can hurt. But the way I see it, you can either run from it or learn from it" Rafiki