Internet service providers (ISPs) are being forced to devote more and more of their time to tackling spam email, it has been reported.
According to the European Network and Information Security Agency (Enisa), more than 95 per cent of all messages sent each day can be categorised as bulk mail.
The organisation says spam issues account for more than ten per cent of all helpdesk enquiries received by ISPs.
In addition, 70 per cent of such firms say the problem is "significant" or "extremely significant" for their operations.
Dr Udo Helmbrecht, Executive Director at Enisa, said spam remains "an unnecessary, time consuming and costly burden" for ISPs and broadband users.
He added: "Email providers should be better at monitoring spam and identifying the source. Policy-makers and regulatory authorities should clarify the conflicts between spam-filtering, privacy, and obligation to deliver."
According to Project Honey Pot, spam email is delivered unevenly throughout the week, peaking during the early afternoon on Mondays.