The future of email as a means of communication could be threatened by a raft of new technologies and legislation banning spam, according to web experts.

New EU legislation comes into effect this October, outlawing unsolicited emails used for marketing purposes. A range of software companies are now also offering net users new ways to block it from their inboxes.

Earthlink last week became the first major American internet service provider (ISP) to introduce a 'challenge response' system that checks messages against the user's address book, and blocks anything it does not recognise. Several smaller software companies are offering similar filtering software.

Cloudmark's SpamNet takes a different approach, using the judgment of its membership, around 500,000 people, to decide whether messages are legitimate or not. It warns users about the judgment and gives them the option to accept the email if they wish.

Critics warn that users risk losing important messages simply because their addresses are not recognised.

Karl Auerbach, director of internet policy board ICANN, said the web was 'balkanising', with communication being increasingly limited to 'communities of trust in which traffic is accepted only from known friends'.

On the plus side, owners of opt-in email lists such as specialist subject newsletters should experience an upsurge in interest from marketers who will no longer be able to use their own lists legally.

Source: http://wired.com/news/culture/0,1284,59156,00.html