Most home users on cable or DSL connections run Windows. These computers can be infected through viruses and worms to act as spam sewers sending out mail. Current statistics show that most of the unwanted mail we see today originate from these computers and not from open relays which were previously the prime target for sending out spam.


Greylisting is based on the principle that unlike legitimate mail servers, virus-infected computers sending out mail do not retry sending their message if there is a delivery error on the first try. Our appliances target Windows zombies by not accepting mail from them on the first delivery attempt (greylist).