The temperature is rising in inboxes as spammers attempt to promote a summer of 'love'.
Sex is on the minds of spammers this summer
Pornographic spam has risen by almost 350% since June according to e-mail filter firm Clearswift.
In a possible attempt to keep up with demand, the number of junk e-mails offering Viagra has also risen significantly.
"It is baffling why there is such a huge uprise," said technical director of Clearswift Alyn Hockey.
Randomness of spam
One of the reasons for the upsurge in porn e-mails could be down to the fact that the months preceding June were unusually quiet in terms of spam.
"The spammers could have been spending time developing their messages and ramping up," said Mr Hockey.
Spammers appear to be purposefully increasing pornographic output during the summer months.
Last summer, there was also a peak for porn in the month of June, and January of this year also saw an increase.
"The trend seems to be for it to peak every six months but as to why, this just seems to be down to the randomness that is spam," said Mr Hockey.
Viagra manufacturer Pfizer is taking legal action against spammers
The amount of counterfeit Viagra being offered by spammers has prompted manufacturer Pfizer to launch a legal campaign against them.
Its own research found that a quarter of men believed that the pharmaceutical giant was responsible for sending Viagra spam.
More carefully targeted advertising is becoming a trend in the spam industry, which also tends to advertise products such as games in the lead up to Christmas.
Diets take centre stage in inboxes after the Christmas binge.
"Spammers do seem to know the time of year to target certain products," said Mr Hockey.
According to Clearswift's yearly review, despite its summer peak, porn spam is on the decline overall.
It accounts for around 5% of spam, compared to financial and healthcare spam which accounts for 39% and 31% respectively.