Four of the largest ISPs in the US are to offer a service that charges businesses for guaranteed delivery of their emails to bypass spam filters.

Comcast, Cox Communications, Time Warner Cable’s Road Runner and Verizon are to offer a service that certifies delivery. It will cost the sender a quarter of a US cent per email.

‘This enables us to help restore trust and makes it easier for consumers to identify legitimate email messages,’ said Peter Castleton, director of Verizon’s consumer broadband services.

The scheme is targeting large corporations and financial institutions who send mass mailings that are most likely to be caught in spam filters.