Via CNet – The SpamHaus Project – a U.K.-based antispam compiler of blacklists – says that a particularly virulent type of spam Trojan has recently been released onto the ‘net, and some are forecasting a dramatic increase in spam soon. Money quote:
This "zombie" computer is then used to send spam
via the mail server of that PC’s Internet service provider. This means
the junk mail appears to come from the ISP, making it very hard for an
antispam blacklist to block it.
Previously, zombie PCs have been used as mail servers themselves, sending spam e-mails directly to recipients.
"The Trojan is able to order proxies to send spam upstream to the ISP," said Steve Linford, director of SpamHaus.
…
This will cause serious problems for the e-mail infrastructure, as it
is impractical to block mail with domain names from large ISPs. Linford
predicts that ISPs will see a growth in the volume of bulk mail they
send and receive over the next two months, with spam levels rising from
75 percent of all e-mail to around 95 percent within a year.