Big net firms are trying to stop spammers by charging to deliver e-mail messages.
Organisations such as the American Red Cross have signed up
AOL and Yahoo plan to charge fees of up to one cent (US) per message to those that sign up for the service.
Paying the fees means that messages will not go through spam filters, are guaranteed to arrive and will bear a stamp of authenticity.
Both AOL and Yahoo said they would start offering the service within the next few months.
The optional charging plan is meant for those organisations that send a lot of e-mail and do not want their messages mistaken for spam. Organisations that do not want to sign up will be able to send mail the old-fashioned way.
The service is also intended to act as protection against so-called phishing gangs that send e-mail messages disguised to look like they come from legitimate organisations.
Under the plan, senders of e-mail will be charged fees ranging from one-quarter of a cent up to one cent to get messages through to AOL and Yahoo users. Despite the low fees, the service is likely to generate huge amounts of money for AOL and Yahoo.
In return for the fee, AOL and Yahoo will not send the messages through spam traps and filters that typically strip out all images and weblinks in an e-mail.
Net firms take these steps to shield people from unwanted pornographic pictures; to remove specially crafted images that report back to spammers that an e-mail address is live; and to take out booby-trapped weblinks that take people to phishing websites.
All the messages that are paid for will bear a stamp saying they are authentic. AOL and Yahoo have signed up with tech firm Goodmail Systems, which will run the service on their behalf.
The service is intended to tackle spam by making it expensive to send messages. Currently so many e-mail messages can be sent for free that tiny response rates mean spammers can easily make money.
The idea of charging for e-mail is just one of many methods used to tackle spam. Yahoo has also signed up for a system which only accepts e-mail from net sites it knows are legitimate senders of mail.
This is intended to tackle those spammers, up to 70% according to some estimates, that use hijacked home PCs to route their e-mail messages.