A post mount mailbox has a post and a base. Also, post-mount mailboxes are installed in the ground on your curbside. Post-mount mailboxes are the most convenient and modern mailboxes. They allow efficient and quick delivery if installed at the right place on the curb. However, they are not huge and rock-solid like community mailboxes but still can hold multiple letters at one time.
Source: Decorative Post-Mount Mailboxes