Is the cost of false positive spam detection high enough to get the average user to bother verifying CentMail stamps?
This depends on how many people are stamping their mail. If stamping were universal then stamp verification would likely become the primary spam filtering attribute. At the other extreme, with very few CentMail users, there’s little incentive. Somewhere in between is a threshold. Since senders have an independent reason to use CentMail (to promote their charities) it remains to be seen whether that motivates enough early adoption to cross that threshold. See [2] for a recent survey of the cost of false positives. • What happens to people who continue to send unstamped email? CentMail does not shut out users who send unstamped email. Especially at first, CentMail’s spam-fighting value will be in avoiding false positives. Sending unstamped mail just means forfeiting that protection against your message being falsely labeled as spam. Only when CentMail becomes so popular that a lack of a stamp is strong evidence of spam is there pressure to stamp all mail. • Would CentMail be a barrier to
