Japanese police have arrested a "prolific spammer" who allegedly bombarded inboxes with hundreds of millions of messages punting internet gambling and dating sites.

Investigators reckon Yuki Shiina, 25, sent as many as 2.2 billion spam messages using what appears to be rudimentary spamming techniques. He allegedly purchased a list of 600,000 email addresses for a pricey ¥100,000 ($927), earning ¥2m ($18,540) through a subsequent spamming campaign, security vendor Sophos reports.

Shiina reportedly faked the message headers of junk mail he sent in a bid to avoid detection, an offence against local anti-spam laws. There's no mention of the use of compromised machines to send spam - standard practice for junk mail scumbags over recent years, and a powerful technique to frustrate both basic spam blocking and investigatory techniques.

Complaints from a local ISP over the volume of junk mail it was processing resulted in an investigation that led onto Shiina's arrest by Tokyo's finest.

The availability of appropriate anti-spam laws in Japan is noteworthy given the country's apparent lack of anti-malware laws. Last month, Kyoto police uncovered a plot to infect users of Winny P2P file-sharing network with a Trojan horse that displayed images of popular anime characters while wiping music and movie files. The three suspected perps were charged with copyright violation rather than virus distribution.

Shiina's arrest is not the first made in Japan over alleged junk mail offences. Four men suspected of sending an internet-congesting 5.4 billion spam emails to promote a dating website were arrested in January 2007. ®

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