Microsoft Chairman Bill Gates is continuing his anti-spam war, promising in an interview published on Thursday to implement a Microsoft-Research-developed scheme that would charge spammers for sending junk mail.

Gates also said in the same interview that Microsoft is considering another research-developed technology that would delay by a number of seconds the delivery of spam to users' inboxes.

The pay-per-spam scheme is definitely the more radical approach. Microsoft Research (MSR) has been dabbling for years with the concept of making spammers pay: in cash, in compute cycles and/or in memory cycles.

Microsoft Research's idea for this is called "Penny Black."

Read More About Penny Black Here

Spam costs users time and network providers money. Microsoft wants to shift the cost burden back onto the spammers.

In theory, this could work in a variety of ways: by requiring senders to pre-compute how much they would be willing to pay to send a certain message; by charging senders to pay after they have submitted a message; and/or by requiring senders to "buy" a "ticket" that would pre-authorize them to send a message.

At least one other company already is selling a solution that is nearly identical to Penny Black.

CruelMail, LLC, a Yardley, Penn., company that offers "spam-proof email accounts." CruelMail's "NetPostage,." for which a patent is pending, according to the company, is an electronic equivalent of a postage stamp.

In conjunction with NetPostage, CruelMail allows users to set of a Free Pass List that allows certain, predesignated individuals to send e-mail for free to a customer's CruelMail.com account.

"The rest will have to pre-pay a delivery fee in order to reach your mailbox. We let you set the fee and will collect it for you. Setting it high enough (does $100K sound high enough?) will prevent any spam from reaching you," says the company on its site.

Microsoft has taken a number of steps, as of late, to put its money where its mouth is, in terms of spam.

Last fall, the company added new filters to its MSN 8.0 service to improve junk mail filtering. Earlier this month, Microsoft sued 15 alleged spammers for punitive and monetary damages. Earlier this week, Gates released another of his corporative missives, this one pointing out Microsoft's commitment to targeting spam on the legal front, as well as on the technology front. And the 2003 versions of Outlook and Exchange that are due to ship in the coming months will include additional spam-filtering capabilities.