I agree the mailbox needs to be updated, both internally, how the mail itself works in your box, and appearance-wise.
We have had 5 expansions without any update to the mail system, and its overdue.
Likewise, the mailbox itself is overdue for an update. Right now we only have 2 mailbox choices for housing, so the players who can make those basically have a monopoly on them.
Why can't we have Loporrit mailboxes?!? That would fit in with some of the lore.