Speaking of penis pills: What to make of the most notorious spam type of the early 2000s, so common that it appeared on AOL’s list twice, as “Viagra online” and “Online pharmacy?”

Viagra spam — much of which was purely fraudulent — didn’t lead national interest in “male enhancement,” but instead followed memorable, widely distributed advertising campaigns on TV, radio and in print. Today, the clearest heirs to the legacy of the endless “C1al1$,” “VI-@gra” and “R0ga1ne” messages — not to mention pitches for weight-loss pills and magical vitamins — are lavishly funded start-ups that hawk white-label vitamins, or newly generic erectile dysfunction and hair-loss pills, saturating social media feeds, subway cars and billboards with winkingly provocative subject lines.

The Financial Spampocalypse

A few years later, in 2007, as the next financial crisis loomed, male enhancement met its match, at least for a moment. According to a report from Bitdefender, a cybersecurity firm, the most common text-based spam subject was still “drugs (sex-related).” Spammers, however, had recently shifted tactics. “Image spam is now the medium of choice,” the report said, describing messages in which text was hidden inside image files. Of the new image-based spam, the firm said, 75 percent concerned a single subject: stocks.

The closer to the present we get, the less confident, and more paranoid, the spam folder sounds. In 2016, according to Kaspersky Lab, a Russian cybersecurity firm, notable spam trends included direct solicitations from (purported) Chinese factories, which, despite their irrelevance to most recipients, reached countless millions of people. Then, of course, there was the election.

“Donald Trump became one of the main topics for the majority of spam emails related to politics,” the company said in mid-2016. “In these emails, spammers told their targets about Mr. Trump’s unique methods of making money and invited them to copy Mr. Trump with their own business.”

So What Does This Mean for Me?

Absent the benefit of hindsight, the spam folders of 2019 are, naturally, the hardest to read. Spam has proliferated across many more platforms than email, of course. In recent years, spammers using automated calling software, have rediscovered the telephone. While overall email spam volume is down, Mr. Wisniewski described a spam-scape of slick scams and paranoia, where the “spray-and-pray” tactics of old have been abandoned for surgical strikes.