邮号是一种无按键的圆形自然铜管乐器，19世纪至20世纪的邮递员和邮政马车在离开或到达时常会吹响邮号。另外在道路上由于邮政马车时刻表紧凑且速度较快，在大多数国家有优先通行权，故道路上的行人和车辆在听到邮号后须即刻让路，避免发生意外或阻碍通行。

短号即是在邮号形式下添加按键发展而来。莫扎特、马勒均在其音乐作品中使用邮号，最著名的是马勒《第3号交响曲》。

中世纪欧洲屠夫常被委托投递信件，被称为屠夫邮政（Metzgerpost），因此牛角制成的号被用作通知居民的工具，亦表示具备优先通行权。

许多欧洲邮政采用邮号作为标志，亦会作为邮政元素出现在纪念邮票上。

The post horn (also posthorn, post-horn) is a valveless cylindrical brass instrument with cupped mouthpiece, used to signal the arrival or departure of a post rider or mail coach. It was used especially by postilions of the 18th and 19th centuries. Mail coaches had tight schedules and travelled at high speed, given priority of way in most countries. Other road users were required to clear completely out of the way. In this manner, the post horn was employed as a modern-day siren, the sound travelling some distance ahead and giving warning of a fast-approaching mail coach before it could be seen.