Before the internet became universal, Unix machines exchanged mail via UUCP — Unix-to-Unix Copy — a store-and-forward system that dialled other machines over phone lines and exchanged files in batches. Email addresses were written as bang paths: ihnp4!ucbvax!decwrl!user, a literal sequence of machines the message should hop through, separated by exclamation marks (“bangs”). Sending mail required knowing the topology of the network yourself and plotting a route, like giving someone directions before GPS. If you got the path wrong, your message simply vanished into a machine that didn’t know where to send it next. The whole system ran on goodwill, shared cron jobs, and phone bills that made accounting departments weep. The @ syntax of the modern internet replaced it, and nobody who used bang paths mourned them.
