Junk mail now accounts for nearly 70% of e-mails worldwide, according to filtering firm MessageLabs.
Spam is a headache for all and costs businesses dear
Despite efforts in the US to cut down on the sending of unsolicited messages, new laws seem to be having the opposite effect.
Spammers are simply adapting rather than shutting up shop.
"The law goes part way to legitimise spam rather than outlaw it," said Natasha Staley, information security analyst at MessageLabs.
April saw a sharp rise in the amount of spam heading for inboxes around the world, according to MessageLabs, and the overall trend is still up.
"We expect global levels to reach 80% by the middle of the year," Ms Staley told BBC News Online.
40% is healthcare related
37.8% is financial
12.8% is direct products
4.8% is pornography
The US Can-Spam Act, which came into force at the beginning of the year, has been dismissed by experts as ineffectual.
Spammers can adhere to requirements such as providing a legitimate return address without it affecting their business practices.
"The law hasn't had as much of an impact as we hoped. I imagine it will have to be revised as there are wide gaping holes," said Ms Staley.
Despite spam being a global problem, Europe and the US are not singing from the same hymn book when it comes to legislation, said Ms Staley.
The Can-Spam Act requires people to reply to e-mails in order to stop receiving them, while the EU favours a so-called opt-in clause, meaning individuals have to actively request commercial e-mails.
The fact that much of the spam is generated in the US renders the EU law ineffectual.
In March, AOL joined forces with Earthlink, Microsoft and Yahoo to pursue lawsuits against over a hundred of the worst spammers in the US.
"A combination of technology, legislation and the work of industry bodies such as Microsoft's idea to charge one pence for all e-mail will all have an impact," said Ms Staley.
Drugs not porn
There is some evidence that the nature of junk mail is changing.
According to content filtering firm Clearswift, spammers are abandoning porn for the more profitable area of financial spam.
Junk mail offering stock price tips, cheap loans and mortgages accounts for nearly 38% of all spam, while pornography accounts for just 5%.
Healthcare still leads the pack, with promises of Viagra, miracle diets and hair restorers still the spammers favourite, making up 40% of all junk mail.
It is estimated that spam costs US businesses $10 billion in 2003.
British businesses are around £3.2 billion out of pocket because of the amount of junk clogging up inboxes, according to MessageLabs.