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 emerging email markets in poorer countries? It is true that CentMail stamps are “free” only when users already intended to make charitable donations, and in fact CentMail may be prohibitively expensive for users in poorer countries. CentMail, however, does not shut out users who leave their messages unstamped (see Question 26), and we imagine CentMail to work in conjunction with myriad other spam fighting tools and techniques. In particular, CentMail eases the transition to alternative economic approaches, such as sender-posted bonds [3], which ultimately may be better suite
