Redwood City, Calif.-based Clearswift said the latest trick has led to a jump of 180 percent in sex-related spam over the course of the last month.
Most of the spam leads to sites appear to be dating forums for swingers, or available and lonely housewives, and Clearswift says that most include programs that can download spyware onto PCs.
According to Clearswift's latest spam index, 18.08 percent of all spam is sex-related, up from 10 percent in the previous month.
"Aside from the fact that these emails are bogus, clicking on any link within a spam mail can lead to a whole host of unwanted problems,” Clearswift spokeswoman Alyn Hockey said. "They frequently contain malicious programs including spyware or rogue Internet dialers, which can run up huge unexpected bills."
Hockey adds that, over the past 20 months, there has been a variety of spins on the sex spam theme in order to attract surfers to porn websites, ranging from offers of a well-paid career as a porn star, to actually setting up and running an online website.
Hockey also said that the array of bizarre products seen after Christmas — including a dog-translator and a device that turns a coffee table into a kennel — has completely dried up.
The percentage of spam in the "direct products" category remained steady over the past month, declining slightly from 17.85 percent to 14.47 percent.
But, interestingly, software now accounts for more than three-quarters of products offered and 12.03 percent of spam overall.
Also, Rolex watch offers have vanished. After spiking in October, they remained consistent in November, and have since slid into obscurity, Clearswift said. One new arrival, the company said, is phony Sony portable games giveaways.