According to the latest spam-filter test conducted by the Virus Bulletin magazine, spammers are increasingly using web hosting firms to send unwanted emails instead of relying on malware and botnets to send spam.

Virus Bulletin compared delivery rates of spam messages sent from web hosts to other types of spam and concluded that spam sent from web host is over three times more likely to pass through spam filters.

Delivery rates of web host spam remain relatively low, as this type of spam has a 1.04% succession rate compared to 0.29% for other type of spam messages. Still, this difference might be huge given that a single spam marketing campaign sends millions of messages, which results in spammers having better chances to reach more users who will follow their spam emails.

As citied by v3.co.uk, anti-spam test director at Virus Bulletin, Martijn Grooten, said that 1% of messages passing through spam filters is still a low number since the vast majority of spam sent from web hosts is still blocked by spam filters.

Over the last years, the security community has been mainly focused on botnets of home computers. But lately cybercriminals have made a shift in their focus turning more attention to web hosting, which is easier to compromise and has a reliable Internet connection, Virus Bulletin said.

The results of the study suggest that by using web hosts to send unsolicited emails, cybercriminals can notably boost their delivery rates, however, overall, anti-spam protective tools turned out to be very effective in blocking spam emails and of all the anti-spam tools tested, the programs blocked over 97% of spam emails.