Abstract
Spam has become a serious problem to email users all over the world. Most of the daily email messages we are receiving consists of unwanted spam messages. Although there are various methods to reduce the quantity of spam such as filtering, IP-based blocking, or port blocking. It appears that it is impossible to overcome spam.
This thesis proposes an alternative approach to the spam problem: by changing the way email messages are delivered. The change is from a push based approach to a pull based approach. The proposed approach works without the involvement of end users. The vulnerabilities of the new approach are discussed and ways to prevent them are proposed.