A man described as Britain's most prolific spammer was jailed for six years on Wednesday at Peterborough Crown Court.
Peter Francis-Macrae of Cambridgeshire was found guilty of fraudulent trading, concealing criminal property, threatening to destroy or damage property, making threats to kill and blackmail, after a six week trial.
As reported last month, Francis-Macrae was accused of defrauding thousands of people by tricking them into sending him money to register a .eu domain name on their behalf. He was also charged with sending fraudulent emails to companies claiming they had to pay a renewal fee to avoid losing their domain names.
It has been estimated that Francis-Macrae received up to £1.6m through the scams.
Businesses who complained said that Francis-Macrae bombarded them with emails. Police and trading standards officers who investigated told the court that they were threatened with petrol-bombing.
The jury also heard that Francis-Macrae ran the scam from his bedroom at his father's three-bedroom terraced house in St Neots, Cambridgeshire.
According to The Times, Judge Nicholas Coleman told Francis-Macrae: "You deceived hundreds of people of countless thousands of pounds of their money. When investigated, following the countless complaints of your misdeeds, you resorted to threats to kill and a threat to set fire to property, and ultimately blackmail.
"Whoever stood in the way of your criminality became subject to abuse and threats. You are, I think, one of the most vindictive young men I have ever seen," Judge Coleman added.
Spamhaus, a group that identifies spammers and helps ISPs to block their traffic, includes Francis-Macrae on its list of professional spammers.
Francis-Macrae was arrested after threatening Nominet UK, the registry that controls all the .uk domain.
Nominet had warned businesses not to fall for the bogus invoices being sent by Francis-Macrae. He responded by phoning Nominet and threatening to attack its systems with a botnet of 200,000 zombie PCs unless the warning was withdrawn.
Francis-Macrae has also been accused of sending a spam email in 2003 which told people they were about to be billed £399 unless they called a telephone number to cancel the order. The number belonged to Cambridgeshire Police, who had recently arrested Francis-Macrae, and the attack jammed the force's network.