Science - June 2, 2005

Weapon against unwanted e-mail

With the introduction of a ‘greylisting’ system on Friday last week, Facilities & Services now has a new weapon against spam.

The WUR mail servers have to cope with about 200 thousand unwelcome mails each day, and sometimes it is as many as 300 thousand. About 95 percent of these are stopped by the spam filter, but the rest slip through the net and land in users’ mailboxes. By not blindly accepting all e-mail the new system blocks much of the spam as it is sent.

‘Incoming mail is refused for the first two minutes,’ explains Kees Bol of Facilities & Services. ‘Normal mail servers save the original mail and try to send it again after two minutes, and these are then let through. But zombies, hacked computers that are used on a large scale to send spam, do not do this. This makes a big difference, and it means that we can stop much of the spam already the first time round.’

The new system not only reduces the work of the spam filter and the virus scanner, but it also reduces the spread of new viruses. ‘New viruses are often spread by zombies. Because we can hold off this mail we can also prevent the viruses from entering our network and then spreading further.’

Most users will hardly notice any changes, besides fewer unwanted e-mails. The system for the internal network will not change. Only students using the Homewurk student network need to change the settings of their mail programme or send their mail twice.
/ JH