How do you send mail to other save files on super Mario galaxy 2?

In Super Mario Galaxy 2, you can't directly send mail between save files. Each save file operates independently, and mail items are tied to the specific save. However, you can transfer items like the Green Stars or Comet Medals by playing through the game on the other save file, as these items are not transferable. If you want to access certain features or items, you'll need to play through each save separately.