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 pillar box is a type of free-standing post box. They are found in the United Kingdom and in most former nations of the British Empire, members of the Commonwealth of Nations and British overseas territories, such as Australia, Cyprus, India, Gibraltar, Hong Kong, the Republic of Ireland, Malta, New Zealand and Sri Lanka. Pillar boxes were provided in territories administered by the United Kingdom, such as Mandatory Palestine, and territories with Agency postal services provided by the British Post Office such as Bahrain, Dubai, Kuwait and Morocco. The United Kingdom also exported pillar boxes to countries that ran their own postal services, such as Argentina, Portugal and Uruguay.