postbox (outgoing mail)

A physical receptacle into which outgoing mail items may be deposited for collection and subsequent delivery by the postal service. Also known as collection box, drop box, etc. (Wikipedia)

For tagging purposes, distinct from mailbox (incoming mail), which is for incoming mail.

Examples

• Danbooru post #870912: Modern Japanese postbox
• Danbooru post #888398: Older cylindrical version
• Danbooru post #7764205: US postbox on the left