mailbox (mailboxes plural )
1 n-count A mailbox is a box outside your house where your letters are delivered.
(AM)
2 n-count A mailbox is a metal box in a public place, where you put letters and packets to be collected. They are then sorted and delivered.
(mainly AM)
in BRIT, use post box
3 n-count On a computer, your mailbox is the file where your e-mail is stored.
usu sing