The world's computer inboxes were clogged by another 70 billion junk e-mails today, despite the arrest in Seattle of a man federal prosecutors dubbed 'the king of spam".

Robert Alan Soloway, 27, faces a jail term of up to 65 years if he is convicted on a 35-count federal indictment that includes wire fraud, e-mail fraud, money-laundering and aggravated identity theft. He has pleaded not guilty to all charges.

But although internet security experts welcomed the arrest of one of the world's most persistent spammers, they warned web-users that it was unlikely to stem the flood of unsolicited e-mail. Mr Soloway was said to be no longer in the premier league of spammers, his place taken by even bigger junk e-mailers operating with impunity in countries such as Russia and Ukraine.

“In the short term, the effect it’s going to have is more symbolic more than anything else,” said John Levine, co-author of Fighting Spam for Dummies. “Soloway is a large spammer, but hardly the only large spammer.”

Mr Soloway was once on a top 10 list of spammers kept by the Spamhaus Project, a London-based anti-spam organisation and remains on the group's list of 135 international spammers responsible for as much as 80 per cent of all junk e-mail. He ran his e-mail empire from a luxury flat on the Seattle waterfront and drives a top-of-the-range Mercedes.

Commenting on his arrest, Spamhaus described Mr Soloway as a "long-term nuisance on the internet" who had been sending enormous amounts of spam for years. It accused him of using hijacked "zombie" computers - whose owners are typically unaware of any problem - to send countless millions of unsolicited e-mails and fraudulently marketing his spam to businesses as legitimate 'opt-in" services.

A federal grand jury issued the indictment last week after a year-long investigation by prosecutors in Washington State, the FBI and other federal agencies including the Internal Revenue Service and the US Postal Inspection Service.

Prosecutors say that Mr Soloway, who has been refused bail, has sent millions of junk e-mails since 2003 and continued even after Microsoft won a $7 million civil judgment against him in 2005 and the operator of a small internet service provider in Oklahoma won a $10 million judgment. Neither of those awards were paid.

One Spamhaus investigator, Vincent Hanna, said that Mr Soloway may have fallen out of the top ten list but was still considered to be in the top 20. “Most of the Russian gangs seem to have a lot more freshly hijacked computers and are able to deliver much more spam into people’s inboxes,” he said. “The stuff that Robert Soloway had under this control, let’s call it ‘second grade.’”

Patrick Peterson, vice-president of technology at the internet security and anti-spam group IronPort Systems said that was set Mr Soloway apart was his focus on spam designed to sell tools and services for companies and organisations to send their own junk e-mail. “This is a great day for the internet,” Mr Peterson said. .“Everyone involved in clapping those handcuffs on are heroes.”

But IronPort conceded that it had seen no notable drop in the volume of spam since Mr Soloway's arrest on Wednesday, with 70 billion messages in a 24-hour period, unchanged from two weeks earlier. The company said that global spam has doubled from about 36 billion a day last May.

The messages take on many guises - and are not, as they used to be, dominated by adverts for porn sites. Many sell drugs such as Viagra, or rip-offs of them. Other spammers manipulate the stock markets, buying penny stocks and ramping up their prices in a scam known as "punt and dump".

Graham Cluley, a British technology consultant with the internet security vendor Sophos, said the significance of the Soloway case would be in the message it sent to other spammers.

"It's always good when these guys are arrested but there always seem to be people waiting to step into their spamming shoes, so people should not expect less spam in their inboxes," he told Times Online. "It does add to the background radiation, though to the message being sent out to spammers that this is not going to be tolerated, that they might face serious jail sentences."

Mr Cluley said that between 60 and 80 per cent of e-mails received by the average web-user were junk.

"We see a lot of activity from Eastern European and Russian gangs taking control of botnets, the networks of zombie computers, to spew out spam, but this really is a global problem," he said.

"The only way it is ever going to stop is if people stop buying goods sold via spam. The big problem is that spam works - it makes money for the spammers."

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