Spammers outwit blacklist strategy
The latest version of Send-Safe, the notorious bulk-mailing software used by many spammers, has a feature that renders the "blacklist" strategy used by email filtering companies obsolete.
Using the blacklist strategy, all emails from a computer known to send out spam are blocked before they reach internet service providers' systems. Most of these emails come from infected PCs - called "zombies" - controlled by the spammers. Send-Safe, however, now disguises the origin of emails to make it seem like they are coming from the zombie's ISP instead of the infected machine.
Blocking mail from an ISP will block mail from all its customers, so the software effectively makes blacklisting impossible. Aggravating this, emails from ISPs are often "whitelisted", or automatically certified as non-spam.
The latest version of Send-Safe has only been out for a few weeks, but email filtering firm MessageLabs has already seen an increase in spam. Technical director David Banes says it's too early to conclusively chalk this up to Send-Safe.
