Virgin Media customers suspected of hosting malware on their PC will be alerted by a letter, the ISP has revealed.
The ISP, which is working with the Shadowserver Foundation to identify which IP addresses are linked to computers infected with malware, will use the letter to offer advice on how to remove the malicious software.
The advice will detail both free options as well as Virgin's own paid-for service Digital Home Support.
"The letters are on headed paper, so they are obviously from us and they are the first step in the process and we'll be looking at email too," Virgin Media told PC Pro.
"Sometimes email from companies gets missed because people think it is spam or think it is from someone else pretending to be from a company – a letter is a sensible approach."
Virgin Media said the data would remain private and no personal information will be tracked.
"The system tracks viruses, not users, and the information we get is just that an IP address has an infection, whether it's the Zeus bot or something else," the spokesman said.
"We're not tracking people to see where they are going and getting the viruses."