A three-day meeting in Washington on junk electronic mail has closed with a call for immediate action to be taken.
Users can be deluged by unwanted emails
The conference, organised by the Federal Trade Commission, was looking at the proliferation of commercial e-mail and exploring the technical, legal and financial issues that spam raises.
Speakers at the conference painted a gloomy future for e-mail unless the problem of spam is immediately addressed.
A Federal Trade Commission representative said things were worse than they had imagined and without immediate improvements, e-mail could be run into the ground.
Internet providers said it was the sheer number of messages that posed the threat.
There were different views on the best way to tackle the problem of spam, which now accounts for more than 40% of e-mails.
Many at the forum suggested new countrywide legislation was needed in the United States, but others said the only solution was to block spam with new technology.
The forum brought together internet providers, anti-spam campaigners and Washington policy makers, but it also heard from e-mail marketers, who maintained that reputable operators only sent messages to consumers who wanted to hear from them.