Retroarpanetjon-postelrfcspaminternet-historyblocklists
Internet Pioneer Jon Postel's 1975 RFC 706, "On the Junk Mail Problem," Proposed Letting a Computer Refuse Messages From a Host That Floods It
In November 1975, Jon Postel wrote that an Arpanet host had no way to turn away unwanted network messages and sketched a "refuse messages from Host X" command with a per-sender threshold, two and a half years before a DEC sales pitch reached hundreds of Arpanet users in May 1978.
The memo fits on one page. Jon Postel, then at SRI’s Augmentation Research Center, filed it as RFC 706 in November 1975, and the problem he names in the first sentence is that “there is no mechanism for the Host to selectively refuse messages.”
In the Arpanet of 1975, a host was a computer and an IMP was the small switching computer that connected it to the network. Every message addressed to a host got delivered, and the host had to look at each one. “Such a Host could be sent many messages by a malfunctioning Host,” Postel wrote. “This would constitute a denial of service to the normal users of this Host.”
He wanted a host to be able to “decline messages from sources it believes are misbehaving or are simply annoying.” It would tell its IMP “refuse messages from Host X,” and the network would discard the traffic early and send back a “refused” notice. He called the mechanics “an open issue” and offered two versions: the receiving IMP keeps the list, or it forwards the request to the sender’s IMP so the junk never leaves home. A host could lift the block with “accept messages from Host X.”
The trigger is the part that sounds like 2026. A host could start “measuring, per source, the number of undesired messages per unit time,” and when that number “exceeds a threshold,” it would issue the refusal.
Postel was picturing a malfunction. The flood that people actually remember came in May 1978, from a marketer. Brad Templeton, who keeps the original messages and his interview with the sender, says “Possibly the first spam ever was a message from a DEC marketing rep to every Arpanet address on the west coast.” Gary Thuerk of DEC had the West Coast entries of the printed Arpanet directory typed in, and engineer Carl Gartley sent the invitation to DECSYSTEM-20 presentations from Thuerk’s account. The mail program took only 320 addresses, and the rest spilled into the body of the message.
The Defense Communications Agency’s Maj. Raymond Czahor answered in capital letters: “THIS WAS A FLAGRANT VIOLATION OF THE USE OF ARPANET AS THE NETWORK IS TO BE USED FOR OFFICIAL U.S. GOVERNMENT BUSINESS ONLY.” Mark Crispin at Stanford saw the future and had nothing to stop it with: “I can envision junk mail being sent to people who implement Dialnet, and no way it could be prevented or stopped.” His best answer was “the command in your mail reading subsystem which deletes an unwanted message.”
Richard Stallman’s complaint was the length: “Nobody should be allowed to send a message with a header that long, no matter what it is about.” Nobody in those replies brought up Postel’s memo, and the archive doesn’t show whether any IMP ever ran a “refuse messages from Host X” list.
Abuse systems since have kept running into the trade Postel left open: block at the receiver, which is easy but still costs the network, or block at the sender, which saves the network but needs every operator to cooperate. The cheaper the message gets, the more the work slides toward the sender’s side, which is why so much of today’s fight runs through the providers that send the mail and not the people reading it. The question his memo never settled, and that RFC 706 still marks as “an open issue,” is who gets to keep the list.