The campaign directs people to the site, where they can download software that generates traffic to known spammers' websites.
This sits on the user's PC and only runs when the machine is not being used. It is the brainchild of Swedish interactive agency .
Lycos said that the software can not be used to bring down spammers' websites entirely, because it would be illegal, but that it would send out a strong message that spam is unacceptable.
Malte Pollman, director of communication services at Lycos Europe, said: "We believe that the power of the internet community can be mobilised to stop the spammers. The combined effect of individual users targeting these sites will slow them down enormously and make it more difficult for them to clutter up our inboxes with unwanted rubbish."
The targets have been chosen from an international blacklist, so that no innocent parties will be targeted.
Lycos Europe's 20m users will be invited to download the software, but anyone with an internet connection and Windows or Mac OX9 or higher can run the programme.
Calle Sjonel, creative director of Starring, said: "We believe the future of marketing lies in helping companies to do things instead of just helping them say stuff. It's more trustworthy and will engage people in a more honest way."
It is not the first time that web companies have bitten back at spammers. In the US, America Online gave away a Porsche, which had been seized from a convicted spammer, as a prize in a competition.
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