Bukkit

mailbox.* - Gives access to all mailbox commands.
mailbox.user.* - Player can create/remove own mailbox and sending the packages to other players.
mailbox.admin.* - Gives access to admin commands.
mailbox.postman.* - Can create a mailbox for someone else and remove mailboxes which he created.

mailbox.admin.viewlog - Can view a log.
mailbox.admin.removeany - Can remove any mailbox.

mailbox.user.send - Can send a package.
mailbox.user.create - Can create own mailbox.
mailbox.user.remove - Can remove own mailbox.

mailbox.postman.createother - Can create a mailbox for someone else.
mailbox.postman.removeother - Can remove mailboxes which he created.

mailbox.sendtoself - Player can send package to himself.
mailbox.nocooldown - Player does not have the send cooldown.