BT Openworld is to provide a free antivirus and spam-busting service to its customers from the end of October.
The free service is being offered on an opt-in basis.
Research for Brightmail, the company providing the technology to can spam for BT, shows that over half of consumers believe the responsibility for stopping spam lies with internet service providers.
Brightmail also recently signed a deal to provide antivirus and antispam software to Hotmail.
Duncan Ingram, BT Openworld's senior vice president, said: "We are seeing increasing concern from customers about spam and viruses, [which] are fundamentally spoiling the internet experience for people.
"But we are going for the opt-in method because some customers may have their own technology in place."
The Brightmail technology will reside on BT's servers to stop spam flooding customers' inboxes. It uses a network of decoy email accounts to attract and identify the spam.
Spam-filtering rules are then automatically generated and pushed to BT Openworld every five to 10 minutes, keeping inboxes clear of junk email.
Customers can opt in to the free service via the BT Openworld website or its webmail service.
Any spam that is sent to them will be transferred to a separate folder where it is held for 30 days.
During this time the customer can trawl through and look for any emails they want to keep. After 30 days the spam will automatically be deleted.
Emails containing viruses will be cleaned using Symantec technology, and then sent on to the recipient.
The service will be rolled out first to BT Openworld broadband consumer customers, and to Anytime and Surftime narrowband customers by the end of the year.
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