Bang path
The UUCP-era email address, in which the sender spelled out every machine on the way to the recipient, separated by exclamation marks.
An address like ihnp4!decvax!foo!alice meant: send to ihnp4, which sends to decvax, which sends to foo, where the user alice lives. The exclamation mark was called a "bang", hence the name. There was no central directory and no automatic routing — you had to know the way, and the way depended on where you were sitting. Business cards and Usenet signatures therefore tended to give an address relative to a few well-known hubs such as AT&T's ihnp4.
The UUCP Mapping Project published maps of the links and the pathalias tool computed routes from them, but it was patchwork. Domain addresses of the form alice@foo.edu took over in the second half of the 1980s, and the transition produced hybrid monsters mixing !, % and @ in a single address.