We've had articles about setting up systems to make people "pay" to send emails before as a way to stamp out spam, but now IBM is on the case. They've worked out an idea that they think would prevent spammers from sending too many emails. It works by requiring any email sender to pay a small fee to receive an authorization code to send emails to certain addresses. The receiver can put anyone they want on a whitelist, which will exempt them from having to pay. Otherwise, the sender would need to get the authorization code first. It's an interesting plan, but like all such plans would (1) require a massive change in email infrastructure (2) require a massive change in the way people think about and use email and (3) actively discourage some of the nicer aspects of email. Spam is a huge problem that I complain about all the time - but I'm not convinced the "charge for it" solution is a practical one either.