Maybe this is where it starts to change.

Two of the world's largest e-mail providers, America Online Inc. and Yahoo Inc., have said they will soon start giving companies the option to pay for guaranteed delivery of e-mails to the in-boxes of their subscribers. Though designed to foil spammers and scammers, the tactic is drawing a mixed reaction in the online community, with some viewing it as another step away from the free culture that long defined the Internet.

"The Postal Service has been charging for the delivery of mail for decades," said Nicholas Graham, a spokesman for AOL. "This is being advanced as a voluntary option for people who simply want to have their e-mail delivered in a different way."

Graham said the move is a response to AOL subscribers who have complained that they can't tell if items in their e-mail in-boxes are authentic or the work of con artists.

Similarly, last week the popular online classified ads site Craigslist announced it would start charging for the placement of some real-estate ads, to help prevent abuses of the otherwise free system.

"This is what we're stuck with," said Julian Haight, founder of a spam-reporting service called SpamCop, who said such charges might be the only answer in an increasingly complicated online world. He called the AOL and Yahoo move "just another nail in the coffin of e-mail in general" because it "kills the whole openness of the e-mail system on the Internet." Haight said, "It's not good, but it may make their users happier."

E-mails sent through the new service will bear a seal certifying that they are legitimate. With the accompanying seal, recipients can be confident that an e-mail came from, say, the American Red Cross — one early customer of the service — and not from some hacker in Russia trying to trick users out of credit-card numbers.

For companies using the service, the e-mails will cost a penny or less per piece to send. E-mail sent through the program will be handled by a company called Goodmail Systems Inc. and not be subjected to the filtering that most e-mails to AOL subscribers undergo as part of the Internet provider's fight against spam.

AOL is scheduled to launch the service in the next two months. Yahoo did not return calls yesterday about its program.

John Levine, chairman of the Anti-Spam Research Group, said he finds the move to be both "depressing and inevitable."

"What really worries me is the direction it's going," he said. Levine runs a mailing list for members of his church. If AOL's program catches on among other providers as the way to send group e-mails, Levine said, will he someday have to pay to send an invitation to the next potluck dinner?

Paul Heller, president and founder of Heller Information Services, an Internet provider based in Rockville, Md., said the AOL and Yahoo programs are "giving a lot of people the creeps," because Web users have regarded e-mail as a service that was free and open to anyone with an account.

But Heller said he sees AOL's new program as another way of putting advertising in front of subscribers.

"Logically, it's just an extension of advertising that you see on the page when you log on to AOL," he said. "This could be a source of revenues for the big providers who can get away with it."