The message arrived on May 3, 1978. Its subject line was blank. Its sender was Gary Thuerk, a marketing manager for Digital Equipment Corporation (DEC). He had a new computer system to show off, the DECSYSTEM-20. And he had a list: every address on the ARPANET’s west coast nodes, 393 in total. He typed an invitation to a product demonstration in California. He hit send.
The network reacted not with annoyance, but with shock. The ARPANET was a closed ecosystem, a digital commune for researchers and military contractors. Its etiquette was implicit, built on academic collegiality. You did not broadcast. You certainly did not advertise. Thuerk’s act was a category error. It treated a conversational space as an addressable market.
Complaints flooded the Defense Communications Agency, which managed the network. Thuerk was reprimanded. He defended himself, claiming he saved DEC the cost of postage. He was right, in a way he didn’t fully intend. He had discovered the fundamental economic asymmetry of electronic mail: the cost to the sender is negligible, while the cost—in attention, in bandwidth—is distributed across all recipients. The genie was not malicious; it was commercial. It was not yet called spam, but the template was set. A new form of communication had been born, and its first act was to invite you to a sales event.