In the 1980s, automatic telephone dialing technology and lower long-distance rates brought an onslaught of junk telephone calls and junk faxes. It wasn't long before spam email became the new scourge.

By the late 1990s, America Online—then the biggest Internet service in the United States—estimated that one-third of the email it delivered was spam. (Spammers complained in their defense that AOL's own pop-up ads ought to be considered spam, too.) Early anti-spam solutions seem kind of hilarious by today's standards. Microsoft made an inbox that would automatically block messages with subject lines including both an exclamation point and a question mark. AOL urged its users to forward the spam emails they received to TOSSpam@aol.com. "For now," The New York Times cautioned in 1998, "most people should put only a moderate amount of trust in the E-mail system."

These days, we may have better spam filters for our inboxes, but scam messages still reach us—like this baloney that recently sneaked through my Gmail spam filter: "I have inheritance for you Kindly contact me."

Its sender kept the body of the email empty—and instead used the pre-set signature line for the message above. Meanwhile, people are getting text-message spam, comment-section spam, and spam across all stripes of social networks.

If the data we leave behind is the reason these networks are so valuable in the first place, then it makes sense that our online activity is like breadcrumbs for marketers and scam artists. Whereas some European countries restrict marketers from creating advertising profiles using data collected about individuals from their behavior online, no such regulations exist in the United States. So there's huge—and in plenty of cases, perfectly legal—incentive to find pathways to the platforms where your data lives. Naturally, more nefarious attempts to get to your data crop up in the same places where you're already opting to put yourself out there. And so: Spam Facebook accounts make friend requests. And, on Twitter, spambots flock to high-profile hashtags—promising weight-loss tricks and free prizes. Here's a message I recently received over the same text system that sends me government alerts for the District of Columbia:

There's even spam for the people who, yes, still have pagers. (Many of the pagers that doctors now carry have text-message capability, which leaves them vulnerable to unwanted SMS messages.) Then there's next-generation spam that floods popular apps. Snapchat users have reported receiving snaps telling them they are "today's winner," and directing them to a website to "pick your prize." (The site, which is registered with a New York phone number, then asks users to input personal information.) Tinder users have for months complained that the site is overrun by robots that send flirtatious messages before requesting a person's credit card number.

Relationship status: my only match on Tinder was a spambot. — John Brennan (@ActingAnEejit) April 6, 2014

Earlier this year, promoters for the sitcom The Mindy Project advertised the show on Tinder by making people believe they had "matched" with star Mindy Kaling. Though some people may have felt deceived slash heartbroken that the real Mindy Kaling wasn't interested in them, this kind of advertisement isn't spam per se. The battle against spam requires us to define a rather slippery practice. When does a message cross over from advertising to fraud? Which messages are protected by the right to free speech?