A new e-mail virus capable of turning infected personal computers into "spamming" machines emerged on Friday targeting corporate and home users in Europe and the United States, a computer security expert said.

Anti-virus software makers Trend Micro reported that tens of thousands of its corporate computer users in France and Germany were hit on Friday afternoon by the virus, dubbed "Mimail.C." By 11:30 a.m. ET on Friday, there were reports of infections in the United States too, said Raimund Genes, European president of Trend Micro.

The firm had a "medium risk" rating on the bug. "We may be upgrading it to high risk if it spreads in the U.S.," he added.

The virus carries the subject message line "our private photos ???." Opening the e-mail triggers the virus into action.The virus installs an SMTP, or simple mail transfer protocol, program on an infected PC that turns the computer into a type of e-mail computer server capable of sending out torrents of virus-infected messages, Genes said.

The e-mail has spread quickly because it spoofs e-mail addresses, making it appear as if the e-mail comes from a friend or co-worker. "It's an old spammers trick," said Genes.

The virus is not believed to be particularly damaging to the infected computer, but it has the potential to unleash a flood of virus e-mails that could bog down corporate networks, Genes said.

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