There seems to be no end in sight to the diet of spam that plagues the inboxes of millions of people.
More than half of the total number of e-mails sent in May were unsolicited messages, according to net filtering firm MessageLabs.
It found that that 55% of e-mails it scanned in May were spam, up from just under 40% in April.
Junk messages are a major nuisance for anyone with an e-mail address, as well as costing firms huge amounts of money in delays and lost production.
On the up
A recent survey found that it was one of the most irritating aspects of working life in the UK, with spam ranking behind traffic jams and long working hours as causing stress for staff.
The bad news is that the number of unsolicited messages is going up, rather than down.
MessageLabs scanned about 134 million e-mails in May. It found that virtually one in every two e-mails was spam.
Junk messages now exceed real e-mails
This amounted to an increase of almost 40% compared to the figure in April.
The growing number of junk messages has prompted big internet service providers such as AOL and MSN to offer programmes to weed out the unwanted mail.
They are also taking to the courts to try to stop the junk. Lawsuits by Microsoft and AOL against suspected spammers are still making their way through the courts.
AOL has already had some success. In December it won nearly $7m (£4.3m) in damages from a company which sent AOL subscribers almost a billion unwanted e-mails touting adult websites.
Governments are also getting involved in the fight against spam. From October, a European Union directive will make unsolicited e-mails illegal across member states.
By October the UK is looking to introduce strict new rules about how personal e-mail details are used to try to curb unwanted and unsolicited e-mail.