邮箱，是常见于街道上，收集外寄信件的邮政设施，寄信人若果不便去邮政局，可以把信件投入到就近的邮箱，邮差会定时来邮筒收集信件，回邮局，再分类、运输及派送。 邮箱是邮政局的固定资产，它是便民设施。

为了向公众展示统一的形象，邮政管理部门通常选择特定的颜色，使公众从总体上识别其服务。从目前各国邮政邮箱的主流颜色来看，红色是使用最为广泛的颜色。中华人民共和国的邮箱颜色统一为绿色。

邮箱有多种类型，包括：

A post box (British English and others, also written postbox; known in the United States and Canada as collection box, mailbox, letter box, or drop box) is a physical box into which members of the public can deposit outgoing mail intended for collection by the agents of a country's postal service. The term post box can also refer to a private letter box for incoming mail.