Well... Your character do wants to get mail, right? That's why you need a mailbox! If you want to send/receive mail, you need one! Simply make one mailbox for each house and put in it who can receive letter from it. No every family lives together (Ie: Keith Leblanc doesn't live in the Leblanc Household).

Mailbox can be used for the following:
- Receive/Send letters
- Receive/Send Invitation
- Receive/Send Advertisement
- Anythign else you see fit with a mailbox!

This will help you giving a message to a lot of people at the same time without having to RP it everywhere. And since very few resident of Nivani Island have Facebook, that's the only way they can receive invitations without directly speaking to the one hosting.