You get mail from your friends on your birthday, wedding, new years, etc. Also sometimes you randomly get 'Van's favorite' which is a wine you use when you connect with AWL using Game Cube.Van's Favorite is only in MFoMT
This is actually one of the ONLY HM games where you get mail :/
, if I remember correctly.
I wish you could get mail in more of the games, I get inexplicably excited whenever I see that I have something in my mailbox...
But yeah, I've only ever received Van's Favorite in MFoMT.
Edit: FFFFFF- Didn't realize this was over 10 days old, I apologize.