New guidelines have been published to help the fight against that most ubiquitous of cyber pests, the spammer.

The Messaging Anti-Abuse Working Group has compiled a list of best practices which it is sending to ISPs.

They include recommendations to use separate servers for received and forwarded emails as well as urging internet providers to post their spam policies on the web.

The guidelines are hoped to help in the fight against spam, which has been estimated to account for over 90% of all email content.

But they will also protect consumers from getting "unnecessarily or unintentionally'" blocked.

More than 230 abuse and privacy professionals from ISPs, email providers and vendors from 18 companies attended a meeting to finalise the new papers.

Richard Cox, from UK anti-spam group Spamhaus, told the BBC: "These are very significant recommendations and they are coming from a well-respected body so there is not much excuse for not following them".