This post was significantly updated in 2026 to reflect new information. An archived version from 2016 is available for reference here.
- Tension: Email marketing has been around for almost 40 years, yet marketers still repeat the same consent and relevance mistakes that made the first message infamous.
- Noise: The industry obsesses over open rates and deliverability benchmarks while ignoring the deeper question of whether recipients actually want what they’re receiving.
- Direct Message: The inbox is a trust relationship, and every campaign that breaks it chips away at the channel’s extraordinary value.
To learn more about our editorial approach, explore The Direct Message methodology.
On May 3, 1978, a marketing manager named Gary Thuerk sent a single message to 393 users on ARPANET, the precursor to the modern internet, promoting Digital Equipment Corporation’s new DECSYSTEM-20 computer line.
It was written entirely in capital letters. It was unsolicited. And it generated roughly $13 million in sales for DEC.
It also generated an immediate flood of complaints, a formal rebuke from a U.S. Defense Communication Agency representative, and a promise from Thuerk that he would never do it again.
He had, without meaning to, invented both email marketing and spam in the same keystroke. Nearly half a century later, email marketing has become a commercial discipline, and the channel now delivers an average ROI of $36 to $42 for every dollar spent.
The question worth asking is why, despite those remarkable returns, one in six marketing emails still never reaches the inbox. The answer is hiding in plain sight inside that 1978 message.
The contradiction built into the channel’s foundation
Thuerk’s email succeeded commercially and failed socially at the same time. That tension has never fully resolved itself.
What he demonstrated was that mass email could move product at scale, and every marketer who came after him absorbed that lesson enthusiastically.
What the industry absorbed far less readily was the second lesson buried in those immediate complaints: the recipients had not agreed to be contacted, and they resented it.
That resentment is structural, not incidental. The inbox is one of the few digital spaces people still experience as genuinely personal.
Unlike a social feed that feels like a public square, email arrives in a space where people expect correspondence from people and organizations they have chosen to hear from.
When something arrives uninvited, it registers as an intrusion rather than an opportunity, regardless of how relevant the offer might be.
The 1978 message made this dynamic visible for the first time. Thuerk’s list was composed of legitimate ARPANET users who were, in theory, precisely the kind of technology professionals who might want to know about a new minicomputer system.
The targeting was reasonable by any modern standard. The problem was consent. The recipients had no expectation of receiving commercial messages on a network built for academic and military exchange, and no framework existed for opting out. The backlash was less about the content than about the relationship being violated.
Decades later, that same violation remains the defining fault line in email marketing. Research finds that the top two reasons consumers unsubscribe are receiving too many emails and receiving emails that feel irrelevant to them.
Both are consent failures in different forms: one ignores how often a person wants to hear from a sender, and the other ignores whether they wanted that message at all.
How the metrics distract from the real question
The email marketing industry has developed a sophisticated vocabulary for measuring everything except the problem that matters most.
Open rates, click-through rates, bounce rates, and deliverability benchmarks are all useful signals, but they measure the symptoms of broken consent rather than consent itself.
Consider what the deliverability crisis actually represents. According to Validity’s 2024 Deliverability Benchmark, Gmail’s inbox placement dropped from 89.8% in early 2024 to 87.2% by Q4, following stricter enforcement of bulk-sender authentication rules.
Marketers responded by investing heavily in technical compliance: SPF records, DKIM authentication, DMARC configuration. These are legitimate and necessary steps. But they address a platform’s technical requirements, not a recipient’s human ones.
The spam filter is, in a sense, a mechanical proxy for a human judgment the industry has been reluctant to make for itself.
When 69% of users report an email as spam based solely on the subject line, as research from Invesp shows, they are making a quick relevance determination that no algorithm fully captures. The filter catches what slips through when senders prioritize volume over relationship.
The original 1978 email is a useful case study here precisely because it had no filters to defeat. It arrived directly in every recipient’s inbox because infrastructure, not permission, was the only barrier. The complaints that followed were the unmediated response of people who had not been asked if they wanted to be contacted.
Modern spam filters are the industry’s attempt to automate that same human refusal at scale. The arms race between marketers and filters is, at its core, a proxy for a consent conversation the industry still has not fully committed to having.
The original email’s accidental lesson
The inbox has always been a trust relationship. The marketers who treat it that way consistently outperform those who treat it as a broadcast channel, and they always have.
Thuerk’s email was blunt, uppercase, and technically primitive. But it worked because the underlying offer was real and the audience, however grudging, was genuinely qualified. The $13 million in sales did not come from deception. It came from relevance delivered without permission.
The lesson the industry drew from this was that relevance was enough. The lesson it should have drawn is that relevance plus permission is where the actual value compounds.
What the 1978 message still requires of us
The first spam email was not malicious. It was optimistic in the way that a lot of early digital marketing was optimistic: the technology exists to reach people at scale, so reaching people at scale must be good.
What it did not account for was that the value of reaching someone depends entirely on whether that person experiences the contact as welcome.
That recalibration is available to every email marketer right now. It means treating list hygiene as a relationship practice rather than a technical one, and removing contacts who have gone quiet rather than continuing to pursue them.
It means sending less to the people who are engaged rather than more to everyone who has not unsubscribed.
It means designing opt-in experiences that set honest expectations about frequency and content, because a subscriber who knows what they signed up for is a different kind of asset than one who was nudged into a checkbox.
Spam accounted for nearly 46% of all global email traffic as recently as 2023, according to Statista. That figure is a measure of how thoroughly the industry absorbed Thuerk’s commercial lesson and how incompletely it absorbed his social one.
The channel’s return on investment is real and well-documented. So is the erosion of inbox trust every time a marketer treats permission as a technicality rather than a foundation. The first email campaign launched both possibilities simultaneously.
Nearly fifty years later, every send is still a choice between them.
