Dr Lindsay Marshall, of Newcastle University, England, warns that people will stop using e-mail unless tougher measures are taken to curb the spiralling amount of spam worldwide.
The new European law, making 'spamming' a criminal offence, takes effect on Thursday 11 December. Dr Marshall says it is a step in the right direction but that it will have virtually no effect of the amount of spam e-mail users receive.
'The problem is that almost all spam originates from outside Europe, particularly the USA, but this law applies only to the European Union. This law is the right idea in principle but to be honest, it will have no noticeable effect,' he said.
'If spam continues to increase, we will stop using e-mail in the same way that we would stop answering a phone that rang continuously,' said Dr Marshall, who recently found 3,000 e-mail messages in his mailbox when he returned from a two-week holiday.
'Even if the Americans introduced a similar law, the spamming industry there would simply move to another country, so the law alone is not a solution.'
Dr Marshall, a senior lecturer in computing science and a research specialist in computer networks, said that a series of measures should be taken to make it much tougher for spammers to make a profit. This would not eradicate spam but would limit its growth.
Measures could include putting pressure on all countries to adopt tough anti-spam laws, education programmes for e-mail users and the wider application of spam filters.
Dr Marshall added: 'The problem is that it is very cheap to send a million spam messages and you only need a tiny number of responses to make a profit.
'Better education of e-mail users is important because people should never respond to spam and they need to know the most effective ways of filtering it out.'
The Privacy and Electronic Communications Regulations 2003, which takes effect in the UK on 11 December 2003, is a European Commission Directive which makes it illegal to send unsolicited e-mails, with unlimited fines for persistent offenders. Companies must get permission from an individual before they can send them an e-mail or text message. However, the regulations do not cover business e-mail addresses.