Remove the mail restriction in its current iteration of requiring real life money to unlock to:
Semi-restrict it to X amount of mail a day at max level.
Benefit: allow people to actually use a core feature in a limited capacity will take some of the sting of the full system being locked behind a paywall.
Allow it to be unrestricted after charging your account with NC coin from ANY source not just Coin purchased through the in-game store.
Benefit: Actually make the in the game message and support article give accurate information.